Polyethylene and catalyst composition for its preparation

ABSTRACT

A polyethylene which comprises ethylene homopolymers and/or copolymers of ethylene with 1-alkenes and has a molar mass distribution width M w /M n  of from 5 to 30, a density of from 0.92 to 0.955 g/cm 3 , a weight average molar mass M w  of from 50000 g/mol to 500 000 g/mol and has from 0.01 to 20 branches/1000 carbon atoms and a z-average molar mass M z  of less than 1 million g/mol, a process for its preparation, catalysts suitable for its preparation and also films in which this polyethylene is present.

This application is the U.S. national phase of International ApplicationPCT/EP2005/004406, filed Apr. 25, 2005, claiming priority to GermanPatent Application 102004020524.8 filed Apr. 26, 2004, and the benefitunder 35 U.S.C. 119(e) of U.S. Provisional Application No. 60/587,533,filed Jul. 13, 2004; the disclosures of International ApplicationPCT/EP2005/004406, German Patent Application 102004020524.8 and U.S.Provisional Application No. 60/587,533, each as filed, are incorporatedherein by reference.

DESCRIPTION

The present invention relates to a novel polyethylene, a catalystcomposition and a process for its preparation, and also to fibers,moldings, films or polymer mixtures in which this polyethylene ispresent.

Ever higher demands are made of the mechanical strength of filmscomprising polyethylene. In particular, products having a high stresscracking resistance, impact toughness and stiffness which areparticularly suitable for the production of films for food packaging,are required. The requirement of simultaneously good stress crackingresistance and stiffness is not easy to meet, since these properties runcounter to one another. While the stiffness increases with increasingdensity of the polyethylene, the stress cracking resistance decreaseswith increasing density.

Stress crack formation in plastics is a physicochemical process whichdoes not change the polymer molecules. It is caused, inter alia, bygradual yielding or untangling of the connecting molecular chains.Stress crack formation occurs less readily the higher the mean molecularweight, the broader the molecular weight distribution and the higher thedegree of molecular branching, i.e. the lower the densities. It occursless readily the longer the side chains themselves. Surface-activesubstances, in particular soaps, and thermal stress accelerate stresscrack formation. On the other hand optical properties, like transparencygenerally decrease with increasing density.

The properties of bimodal polyethylenes depend, firstly, on theproperties of the components present. Secondly, the quality of mixing ofthe high molecular weight component and the low molecular weightcomponent is of particular importance for the mechanical properties ofthe polyethylene. A poor mixing quality results, inter alia, in a lowstress cracking resistance and adversely affects the creep behavior ofpressure pipes made of polyethylene blends.

It has been found to be advantageous to use blends of a high molecularweight, low-density ethylene copolymer and a low molecular weight,high-density ethylene homopolymer, which have good stress crackingresistances, for hollow bodies and pressure pipes, as described, forexample, by L. L. Böhm et al., Adv. Mater. 4, 234-238 (1992). Similarpolyethylene blends are disclosed in EP-A-100 843, EP-A 533 154, EP-A533 155, EP-A 533 156, EP-A 533 160 and U.S. Pat. No. 5,350,807.

Such bimodal polyethylene blends are often produced using reactorcascades, i.e. two or more polymerization reactors are connected inseries, and the polymerization of the low molecular weight componentoccurs in one reactor and that of the high molecular weight componentoccurs in the next (cf. for example, M. Rätzsch, W. Neiβl “BimodalePolymerwerkstoffe auf der Basis von PP and PE” in “Aufbereiten vonPolymeren mit neuartigen Eigenschaften”, pp. 3-25, VDI-Verlag,Düsseldorf 1995). A disadvantage of this process is that relativelylarge amounts of hydrogen have to be added to produce the low molecularweight component. The polymers obtained in this way therefore have a lowcontent of vinyl end groups, especially in the low molecular weightcomponent. In addition, it is technically complex to prevent comonomersadded in one reactor or hydrogen added as regulator from getting intothe next reactor.

The use of catalyst compositions comprising two or more different olefinpolymerization catalysts of the Ziegler type or the metallocene type isknown. For example, it is possible to use a combination of two catalystsof which one produces a polyethylene having a mean molar mass which isdifferent from that produced by the other for preparing reactor blendshaving broad molecular weight distributions (WO 95/11264). Thecopolymers of ethylene with higher α-olefins such as propene, 1-butene,1-pentene, 1-hexene or 1-octene, known as LLDPE (linear low densitypolyethylene) which are formed using classical Ziegler-Natta catalystsbased on titanium are different from an LLDPE which is prepared using ametallocene. The number of side chains formed by incorporation of thecomonomer and their distribution, known as the SCBD (short chainbranching distribution) is very different when using the variouscatalyst systems. The number and distribution of the side chains has acritical influence on the crystallization behavior of the ethylenecopolymers. While the flow properties and thus the processability ofthese ethylene copolymers depends mainly on their molar mass and molarmass distribution, the mechanical properties are therefore particularlydependent on the short chain branching distribution. However, the shortchain branching distribution also plays a role in particular processingmethods, e.g. in film extrusion in which the crystallization behavior ofthe ethylene copolymers during cooling of the film extrudate is animportant factor in determining how quickly and in what quality a filmcan be extruded. The correct combination of catalysts for a balancedcombination of catalysts for a balanced combination of good mechanicalproperties and good processability is difficult to find in view of thelarge number of possible combinations.

The addition of metal components, including late transition metals, toolefin polymerization catalysts based on early transition metals toincrease the activity or stability of the latter catalysts has beendescribed many times (Herrmann, C.; Streck, R.; Angew. Makromol. Chem.94 (1981) 91-104).

The synthesis of branched polymers from ethylene without use of acomonomer using bimetallic catalysts in which one catalyst oligomerizespart of the ethylene and the other copolymerizes the oligomers formed inthis way with ethylene has been described (Beach, David L.; Kissin, YuryV.; J. Polym. Sci., Polym. Chem. Ed. (1984), 22, 3027-42.Ostoja-Starzewski, K. A.; Witte, J.; Reichert, K. H., Vasiliou, G. inTransition Metals and Organometallics as Catalysts for OlefinPolymerization. Kaminsky, W.; Sinn, H. (editors); Springer-Verlag;Heidelberg; 1988; pp. 349-360). The latter reference describes, forexample, the use of a nickel-containing oligomerization catalyst incombination with a chromium-containing polymerization catalyst.

WO 99/46302 describes a catalyst composition based on (a) aniron-pyridinebisimine component and (b) a further catalyst such as azirconocene or Ziegler catalyst and their use for the polymerization ofethylene and olefins.

Another important variable in film processing is the bubble shape. A lotof film properties can be still further improved by switching from the“conventional” method, wherein the bubble is intensively cooledimmediately after leaving the die, to the so called “long stalk” method.In the later method the upper lip of the cooling ring is adjusted togive a large air outlet gap. As a result the cooling air velocity islower than with the conventional method, even as the fan output remainsthe same. The static pressure around the bubble remains relatively high.It prevents expansion and thus leads to the formation of a stalk. Due tothe comparatively small cooling surface, the temperature of the stalkremains high and the orientations of the polymers resulting from theflow in the die are partially relaxed. The frost line hight remainsunchanged. The bubble is inflated uniformly and simultaneously inmachine and transverse direction under intensive cooling immediatelybefore it reaches the frost line. This usually improves mechanicalproperties of the film. On the other hand it is not possible in allextrusion lines to adjust the upper cooling lip and thus the bubbleshape.

The known ethylene copolymer blends still leave something to be desiredin terms of the combination of good mechanical properties, goodprocessability and high optical qualities. It is further desirable tohave films which have similar properties independently from the mode ofextrusion by either the “conventional” or the “long stalk” method.

It has surprisingly been found that this object can be achieved using aspecific catalyst composition by means of which a polyethylene havinggood mechanical properties, good processability and high opticalqualities is obtained

We have accordingly found a polyethylene which comprises ethylenehomopolymers and/or copolymers of ethylene with 1-alkenes and has amolar mass distribution width M_(w)/M_(n) of from 5 to 30, a density offrom 0.92 to 0.955 g/cm³, a weight average molar mass M_(w) of from50000 g/mol to 500 000 g/mol and has from 0.01 to 20 branches/1000carbon atoms and a z-average molar mass Mz of less than 1 million g/mol.

The polyethylene of the invention has a molar mass distribution widthM_(w)/M_(n) in the range from 5 to 30, preferably from 6 to 20 andparticularly preferably from 7 to 15. The density of the polyethylene ofthe invention is in the range from 0.92 to 0.955 g/cm³, preferably from0.93 to 0.95 g/cm³ and particularly preferably in the range from 0.935to 0.945 g/cm³. The weight average molar mass M_(w) of the polyethyleneof the invention is in the range from 50000 g/mol to 500 000 g/mol,preferably from 100 000 g/mol to 300 000 g/mol and particularlypreferably from 120 000 g/mol to 250 000 g/mol.

The molar mass distribution of the polyethylene of the invention can bemonomodal, bimodal or multimodal. In the present patent application, amonomodal molar mass distribution means that the molar mass distributionhas a single maximum. A bimodal molar mass distribution means, for thepurposes of the present patent application, that the molar massdistribution has at least two points of inflection on one flank startingfrom a maximum. The molar mass distribution is preferably monomodal orbimodal, in particular bimodal.

The polyethylene of the invention has from 0.01 to 20 branches/1000carbon atoms, preferably from 1 to 10 branches/1000 carbon atoms andparticularly preferably from 3 to 8 branches/1000 carbon atoms. Thebranches/1000 carbon atoms are determined by means of ¹³C-NMR, asdescribed by James. C. Randall, JMS-REV. Macromol. Chem. Phys., C29(2&3), 201-317 (1989), and refer to the total content of CH₃ groups/1000carbon atoms.

The z-average molar mass M_(z) of the polyethylene of the invention isin the range of less than 1 million g/mol, preferably from 250 000 g/molto 700 000 g/mol and particularly preferably from 300 000 g/mol to 500000 g/mol. The definition of z-average molar mass M_(z) is e.g.published in High Polymers Vol. XX, Raff and Doak, IntersciencePublishers, John Wiley & Sons, 1965, S. 443.

The HLMI of the polyethylene of the invention is preferably in the rangeof from 5 to 100 g/10 min, preferably in the range of from 7 to 60 g/10min and particularly preferably of from 9 to 50 g/10 min. For thepurposes of this invention, the expression “HLMI” refers as known to the“high load melt index” and is determined at 190° C. under a load of 21.6kg (190° C./21.6 kg) in accordance with ISO 1133.

The amount of the polyethylene of the invention with a molar mass ofbelow 1 million g/mol, as determined by GPC, in the standarddetermination of the molecular weight distribution, is preferably above95.5% by weight, preferably above 96% by weight and particularlypreferably above 97% by weight. This is determined in the usual courseof the molar mass distribution measurement by applying the WIN GPCsoftware.

The polyethylene of the invention has preferably at least 0.5 vinylgroups/1000 carbon atoms, preferably from 0.6 to 3 vinyl groups/1000carbon atoms and particularly preferably from 0.7 to 2 vinyl groups/1000carbon atoms. The content of vinyl groups/1000 carbon atoms isdetermined by means of IR, ASTM D 6248-98. For the present purposes, theexpression vinyl groups refers to —CH═CH₂ groups; vinylidene groups andinternal olefinic groups are not encompassed by this expression. Vinylgroups are usually attributed to a polymer termination reaction after anethylene insertion, while vinylidene end groups are usually formed aftera polymer termination reaction after a comonomer insertion. Vinylideneand vinyl groups can subsequently be functionalized or crosslinked, withvinyl groups usually being more suitable for these subsequent reactions.Preference is given to at least 0.5 vinyl groups/1000 carbon atoms,preferably from 0.5 to 10 vinyl groups/1000 carbon atoms andparticularly preferably from 0.7 to 5 vinyl groups/1000 carbon atomsbeing present in the 20% by weight of the polyethylene having the lowestmolar masses. This can be determined by solvent-nonsolventfractionation, later called Holtrup fractionation as described in W.Holtrup, Makromol. Chem. 178, 2335 (1977) coupled with IR measurement ofthe different fractions, with the vinyl groups being measured inaccordance with ASTM D 6248-98. Xylene and ethylene glycol diethyl etherat 130° C. were used as solvents for the fractionation. 5 g ofpolyethylene were used and were divided into 8 fractions.

The polyethylene of the invention preferably has at least 0.05vinylidene groups/1000 carbon atoms, in particular from 0.1 to 1vinylidene groups/1000 carbon atoms and particularly preferably from0.14 to 0.4 vinylidene groups/1000 carbon atoms. The determination iscarried out in accordance with ASTM D 6248-98.

Preferably the 5-50% by weight of the polyethylene of the inventionhaving the lowest molar masses, preferably 10-40% by weight andparticularly preferably 15-30% by weight, have a degree of branching ofless than 12 branches/1000 carbon atoms. This degree of branching in thepart of the polyethylene having the lowest molar masses is preferablyfrom 0.01 to 10 branches/1000 carbon atoms and particularly preferablyfrom 0.1 to 6 branches/1000 carbon atoms. The 5-50% by weight of thepolyethylene of the invention having the highest molar masses,preferably 10-40% by weight and particularly preferably 15-30% byweight, have a degree of branching of more than 1 branch/1000 carbonatoms. This degree of branching in the part of the polyethylene havingthe highest molar masses is preferably from 2 to 40 branches/1000 carbonatoms and particularly preferably from 5 to 20 branches/1000 carbonatoms. The part of the polyethylene having the lowest or highest molarmass is determined by the method of solvent-nonsolvent fractionation,later called Holtrup fractionation as described in W. Holtrup, Makromol.Chem. 178, 2335 (1977) and coupled with IR or NMR analysis of thedifferent fractions. Xylene and ethylene glycol diethyl ether at 130° C.were used as solvents and nonsolvent for the fractionation. 5 g ofpolyethylene were used and were divided into 8 fractions. The fractionsare subsequently examined by ¹³C-NMR spectroscopy. The degree ofbranching in the various polymer fractions can be determined by means of¹³C-NMR as described by James. C. Randall, JMS-REV. Macromol. Chem.Phys., C29 (2&3), 201-317 (1989). The degree of branching is the totalCH₃ content/1000 carbon atoms in the low or high molecular weightfractions.

The polyethylene of the invention preferably has from 0.1 to 20 branchesof side chains larger than CH₃/1000 carbon atoms, preferably side chainsfrom C₂-C₆/1000 carbon atoms, preferably from 1 to 10 branches of sidechains larger than CH₃/1000 carbon atoms, preferably side chains fromC₂-C₆/1000 carbon atoms and particularly preferably from 2 to 6 branchesof side chains larger than CH₃/1000 carbon atoms, preferably side chainsfrom C₂-C₆/1000 carbon atoms. The amount of branches of side chainslarger than CH₃/1000 carbon atoms are determined by means of ¹³C-NMR, asdetermined by James C. Randall, JMS-REV. Macromol. Chem. Phys., C29(2&3), 201-317 (1989), and refer to the total content of side chainslarger than CH₃ groups/1000 carbon atoms (without end groups). It isparticularly preferred in polyethylene with 1-butene, 1-hexene or1-octene as the 1-alkene to have 0.01 to 20 ethyl, butyl or hexyl sidebranches/1000 carbon atoms, preferably from 1 to 10 ethyl, butyl orhexyl side branches/1000 carbon atoms and particularly preferably from 2to 6 ethyl, butyl or hexyl side branches/1000 carbon atoms. This refersto the content of ethyl, butyl or hexyl side chains/1000 carbon atomswithout the end groups.

The ratio of Eta-values of the polyethylene of the inventionEta(vis)/Eta(GPC) is preferably less than 0.95, preferably less than0.93 and particularly preferably less than 0.90. Eta(vis) is theintrinsic viscosity as determined according to ISO 1628-1 and -3 inDecalin at 135° C. Eta(GPC) ist he viscosity as determined by GPC (gelpermeation chromatographie) according to DIN 55672, wherein1,2,4-Trichlorobenzene is used instead of THF and the determination iscarried out at 140° C. instead of room temperature. The Eta(GPC) valueis calculated according to Arndt/Müller Polymer Charakterisierung,München 1996, Hanser Verlag, ISBN 3-446-17588-1 with the coefficients ofthe Mark-Houwing-equation (page 147, equation 4.93) for polyethylenebeing K=0.00033 dl/g and alpha=0.73, which is adjusted to1,2,4-Trichlorobenzene at 140° C. by using the GPC-curve M-eta (page 148and equation 4.94 lower part) to result in the Mark-Houwing-equation(4.93) the value for the intrinsic Viscosity [eta] in Decalin with thevalues K=0.00062 dl/g and alpha=0.7 for Decalin at 135° C.

In the polyethylene of the invention, the part of the polyethylenehaving a molar mass of less than 10 000 g/mol, preferably less than 20000, preferably has a degree of branching of from 0 to 1.5 branches ofside chains larger than CH₃/1000 carbon atoms, preferably side chainsfrom C₂-C₆/1000 carbon atoms. Particular preference is given to the partof the polyethylene having a molar mass of less than 10 000 g/mol,preferably less than 20 000, having a degree of branching of from 0.1 to0.9 branches of side chains larger than CH₃/1000 carbon atoms,preferably side chains from C₂-C₆/1000 carbon atoms. Preferably thepolyethylene of the invention with 1-butene, 1-hexene or 1-octene as theα-olefin, the part of the polyethylene having a molar mass of less than10 000 g/mol, preferably less than 20 000, preferably has a degree offrom 0 to 1.5 ethyl, butyl or hexyl branches of side chains/1000 carbonatoms. Particular preference is given to the part of the polyethylenehaving a molar mass of less than 10 000 g/mol, preferably less than 20000, having a degree of branching of from 0.1 to 0.9 ethyl, butyl orhexyl branches of side chains/1000 carbon atoms. This too, can bedetermined by means of the Holtrup/¹³C-NMR method described. This refersto the content of ethyl, butyl or hexyl side chains or in generalbranches of side chains larger than CH₃/1000 carbon atoms without theend groups. Furthermore, it is preferred that at least 70% of thebranches of side chains larger than CH₃ in the polyethylene of theinvention are present in the 50% by weight of the polyethylene havingthe highest molar masses. This too can be determined by means of theHoltrup/¹³C-NMR method described.

The polyethylene of the invention preferably has a mixing qualitymeasured in accordance with ISO 13949 of less than 3, in particular from0 to 2.5. This value is based on the polyethylene taken directly fromthe reactor, i.e. the polyethylene powder without prior melting in anextruder. This polyethylene powder is preferably obtainable bypolymerization in a single reactor.

The polyethylene of the invention preferably has a degree of long chainbranching λ (lambda) of from 0 to 2 long chain branches/10 000 carbonatoms and particularly preferably from 0.1 to 1.5 long chain branches/10000 carbon atoms. The degree of long chain branching λ (lambda) wasmeasured by light scattering as described, for example, in ACS Series521, 1993, Chromatography of Polymers, Ed. Theodore Provder; Simon Pangand Alfred Rudin: Size-Exclusion Chromatographic Assessment ofLong-Chain Branch Frequency in Polyethylenes, page 254-269.

As 1-alkenes, which are the comonomers which can be present, eitherindividually or in a mixture with one another, in addition to ethylenein the ethylene copolymer part of the polyethylene of the invention, itis possible to use all 1-alkenes having from 3 to 12 carbon atoms, e.g.propene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene,1-octene and 1-decene. The ethylene copolymer preferably comprises1-alkenes having from 4 to 8 carbon atoms, e.g. 1-butene, 1-pentene,1-hexene, 4-methylpentene or 1-octene, in copolymerized form ascomonomer unit. Particular preference is given to using 1-alkenesselected from the group consisting of 1-butene, 1-hexene and 1-octene.

The polyethylene of the invention can further comprise of from 0 to 6%by weight, preferably 0.1 to 1 by weight of auxiliaries and/or additivesknown per se, e.g. processing stabilizers, stabilizers against theeffects of light and heat, customary additives such as lubricants,antioxidants, antiblocking agents and antistatics, and also, ifappropriate, dyes. A person skilled in the art will be familiar with thetype and amount of these additives.

Furthermore, it has been found that the processing properties of thepolyethylenes of the invention can be improved further by incorporationof small amounts of fluoroelastomers or thermoplastic polyesters. Suchfluoroelastomers are known as such as processing aids and arecommercially available, for example, under the trade names Viton® andDynamar® (cf. also, for example, U.S. Pat. No. 3,125,547). They arepreferably added in amounts of from 10 to 1000 ppm, particularlypreferably from 20 to 200 ppm, based on the total mass of the polymerblend according to the invention.

In general mixing of the additives and the polyethylene of the inventioncan be carried out by all known methods. It can be done, for example, byintroducing the powder components into a granulation apparatus, e.g. atwin-screw kneader (ZSK), Farrel kneader or Kobe kneader. The granulatedmixture can also be processed directly on a film production plant.

We have also found the use of the polyethylenes of the invention forproducing films and films in which the polyethylene of the invention ispresent as a significant component.

Films in which the polyethylene of the invention is present as asignificant component are ones which contain from 50 to 100% by weight,preferably from 60 to 90% by weight, of the polyethylene of theinvention, based on the total polymer material used for manufacture. Inparticular, films in which one of the layers contains from 50 to 100% byweight of the polyethylene of the invention are also included.

In general the films are produced by plastification of the polyethyleneof the invention at a melt temperature in the range of from 190 to 230°C., forcing of the plastificised polyethylene through an annular die andcooling. The film can further comprise of from 0 to 30% by weight,preferably 0.1 to 3 by weight of auxiliaries and/or additives known perse, e.g. processing stabilizers, stabilizers against the effects oflight and heat, customary additives such as lubricants, antioxidants,antiblocking agents and antistatics, and also, if appropriate, dyes.

The polyethylenes of the invention can be used to prepare films with athickness of from 5 μm to 2.5 mm. The films can e.g. be prepared viablown film extrusion with a thickness of from 5 μm to 250 μm or via flatfilm extrusion, like cast film extrusion with a thickness of from 10 μmto 2.5 mm. During blown film extrusion the polyethylene melt is forcedthrough an annular die. The bubble that is formed is inflated with airand hauled off at a higher speed than the die outlet speed. The bubbleis intensively cooled by a current of air so that the temperature at thefrost line is lower than the crystallite melting point. The bubbledimensions are fixed here. The bubble is then collapsed, trimmed ifnecessary and rolled up using a suitable winding instrument. Thepolyethylenes of the invention can be extruded by either the“conventional” or the “long stalk” method. The flat films can beobtained e.g. in chill roll lines or thermoforming film lines.Furthermore composite films from the inventive polyethylene can beproduced on coating and laminating lines. Especially preferred arecomposite films wherein paper, aluminium or fabric substrates areincorporated into the composite structure. The films can be monolayeredor multilayered, obtained by coextrusion and are preferably monolayered.

The polyethylenes of the invention are, for example, very suitable forproducing films on blown film and cast film plants at high outputs. Thefilms display very good mechanical properties, high shock resistance andhigh ultimate tensile strength together with very good opticalproperties, in particular transparency and gloss. They are suitable, inparticular, for the packing sector, for example as heat sealing films,both for heavy duty sacks and also for the food sector. Furthermore, thefilms display only a low blocking tendency and can therefore be handledby machines with only small additions, if any, of lubricants andantiblocking agents.

The films of the invention are particularly suitable as stretch films,hygienic films, films for office uses, sealing layers, composite andlaminating films. The films are especially suitable in applicationsrequiring high clarity and gloss such as carrier bags to permit highquality printing, laminating films in foodstuff applications, since thefilms of the invention also have a very low odour and taste level andautomatic packaging films, since the film can be processed on high-speedlines.

The films of the invention with a thickness of 50 μm have preferably ahaze, as determined by ASTM D 1003-00 on a BYK Gardener Haze Guard PlusDevice on at least 5 pieces of film 10×10 cm below 22%, preferably offrom 5 to 21% and particularly preferably of from 7 to 20%. The dartdrop impact of the film with a thickness of 50 μm as determined by ASTMD 1709 Method A is preferably above 80 g, preferably of from 85 to 400 gand particularly preferably of from 90 to 350 g. The clarity of the filmwith a thickness of 50 μm as determined by ASTM D 1746-03 on a BYKGardener Haze Guard Plus Device, calibrated with calibration cell 77.5,on at least 5 pieces of film 10×10 cm is preferably at least 95%,preferably of from 96 to 100% and particularly preferably of from 97 to99%. The gloss 45° of the film with a thickness of 50 μm as determinedby ASTM D 2457-03 on a gloss meter 45° with a vacuum plate for fixingthe film, on at least 5 pieces of film is preferably at least 46,preferably of from 47 to 80 and particularly preferably of from 49 to70.

The scrap obtained during the production of these films can be recycled.Film trimmings are compacted or ground and fed to a side extruder inwhich they are melted and returned to the main extruder. The filmresidues should be reground to grains of a size that can be fed into thefeed section of the processing machinery together with the virginpolyethylene. The films obtained with regrind inventive films in onelayer, do not show any significant deterioration of the propertiescompared to films without regrind.

The polyethylene of the invention is obtainable using the catalystsystem of the invention and in particular its preferred embodiments.

We have also found a catalyst system for preparing the polyethylenes ofthe invention and a process for preparing the polyethylene of theinvention by polymerization of ethylene or copolymerization of ethylenewith 1-alkenes with 3 to 12 carbon atoms in the presence of the catalystsystem. A preferred process for preparing the polyethylene of theinvention by polymerization of ethylene or copolymerization of ethylenewith one or several 1-alkenes of formula R¹CH═CH₂, in der R¹ is hydrogenor an alkyl radical with 1 bis 10 carbon atoms in the presence of thecatalyst system at a temperature of from 20 to 200° C. and a pressure offrom 0.5 to 100 bar, equivalent to 0.05 to 1 MPa. 1-alkenes are e.g.ethylene, propylene, 1-butene, 1-hexene, 4-methyl-1-pentene or 1-octene.

Preferably ethylene is used in the process as the only monomer or as amixture of at least 50% by weight ethylene and 50% by weight or less ofthe 1-alkenes of formula R¹CH═CH₂, preferably one of the 1-alkenes offormula R¹CH═CH₂. Preferably ethylene is polymerised as a mixture of atleast 80% by weight ethylene and 20% by weight or less of the 1-alkenesof formula R¹CH═CH₂.

The process of the invention results in polyethylenes with a lowtransition metal and halogen content due to the high activity of thecatalyst. The polyethylenes therefore show high colour stability,corrosion resistance and clarity.

The present invention further provides a catalyst composition comprisingat least two different polymerization catalysts of which A) is at leastone polymerization catalyst based on a hafnocene (A) and B) is at leastone polymerization catalyst based on an iron component having atridentate ligand bearing at least two aryl radicals with each bearing ahalogen or tert. alkyl substituent in the ortho-position (B).

The invention further provides a process for the polymerization ofolefins in the presence of the catalyst composition of the invention.

Hafnocene catalyst components are, for example, cyclopentadienylcomplexes. The cyclopenta-dienyl complexes can be, for example, bridgedor unbridged biscyclopentadienyl complexes as described, for example, inEP 129 368, EP 561 479, EP 545 304 and EP 576 970, monocyclopentadienylcomplexes such as bridged amidocyclopentadienyl complexes described, forexample, in EP 416 815, multinuclear cyclopentadienyl complexes asdescribed in EP 632 063, pi-ligand-substituted tetrahydropentalenes asdescribed in EP 659 758 or pi-ligand-substituted tetrahydroindenes asdescribed in EP 661 300.

Particularly suitable hafnocenes (A) are hafnium complexes of thegeneral formula (I)

where the substituents and indices have the following meanings:

-   X^(B) is fluorine, chlorine, bromine, iodine, hydrogen,    C₁-C₁₀-alkyl, C₂-C₁₀-alkenyl, C₆-C₁₅-aryl, alkylaryl having from 1    to 10 carbon atoms in the alkyl part and from 6 to 20 carbon atoms    in the aryl part, —OR^(6B) or —NR^(6B)R^(7B), or two radicals X^(B)    form a substituted or unsubstituted diene ligand, in particular a    1,3-diene ligand, and the radicals X^(B) are identical or different    and may be joined to one another,-   E^(1B)-E^(5B) are each carbon or not more than one E^(1B) to E^(5B)    is phosphorus or nitrogen, preferably carbon,-   t is 1, 2 or 3 and is, depending on the valence of Hf, such that the    metallocene complex of the general formula (VI) is uncharged,

where

-   R^(6B) and R^(7B) are each C₁-C₁₀-alkyl, C₆-C₁₅-aryl, alkylaryl,    arylalkyl, fluoroalkyl or fluoroaryl each having from 1 to 10 carbon    atoms in the alkyl part and from 6 to 20 carbon atoms in the aryl    part and-   R^(1B) to R^(5B) are each, independently of one another hydrogen,    C₁-C₂₂-alkyl, 5- to 7-membered cycloalkyl or cycloalkenyl which may    in turn bear C₁-C₁₀-alkyl groups as substituents, C₂-C₂₂-alkenyl,    C₆-C₂₂-aryl, arylalkyl having from 1 to 16 carbon atoms in the alkyl    part and from 6 to 21 carbon atoms in the aryl part, NR^(8B) ₂,    N(SiR^(8B) ₃)₂, OR^(8B), OSiR^(8B) ₃, SiR^(8B) ₃, where the organic    radicals R^(1B)-R^(5B) may also be substituted by halogens and/or    two radicals R^(1B)-R^(5B), in particular vicinal radicals, may also    be joined to form a five-, six- or seven-membered ring, and/or two    vicinal radicals R^(1D)-R^(5D) may be joined to form a five-, six-    or seven-membered heterocycle containing at least one atom from the    group consisting of N, P, O and S, where    the radicals R^(8B) can be identical or different and can each be    C₁-C₁₀-alkyl, C₃-C₁₀-cycloalkyl, C₆-C₁₅-aryl, C₁-C₄-alkoxy or    C₆-C₁₀-aryloxy and-   Z^(1B) is X^(B) or

where the radicals

-   R^(9B) to R^(13B) are each, independently of one another, hydrogen,    C₁-C₂₂-alkyl, 5- to 7-membered cycloalkyl or cycloalkenyl which may    in turn bear C₁-C₁₀-alkyl groups as substituents, C₂-C₂₂-alkenyl,    C₆-C₂₂-aryl, arylalkyl having from 1 to 16 carbon atoms in the alkyl    part and 6-21 carbon atoms in the aryl part, NR^(14B) ₂, N(SiR^(14B)    ₃)₂, OR^(14B), OSiR^(14B) ₃, SiR^(14B) ₃, where the organic radicals    R^(9B)-R^(13B) may also be substituted by halogens and/or two    radicals R^(9B)-R^(13B), in particular vicinal radicals, may also be    joined to form a five-, six- or seven-membered ring, and/or two    vicinal radicals R^(9B)-R^(13B) may be joined to form a five-, six-    or seven-membered heterocycle containing at least one atom from the    group consisting of N, P, O and S, where-   the radicals R^(14B) are identical or different and are each    C₁-C₁₀-alkyl, C₃-C₁₀-cycloalkyl, C₆-C₁₅-aryl, C₁-C₄-alkoxy or    C₆-C₁₀-aryloxy,-   E^(6B)-E^(10B) are each carbon or not more than one E^(6B) to    E^(10B) is phosphorus or nitrogen, preferably carbon,

or where the radicals R^(4B) and Z^(1B) together form an —R^(15B)_(v)-A^(1B)-group, where

-   R^(15B) is

═BR^(16B), ═BNR^(16B)R^(17B), =AIR^(16B), —Ge—, —Sn—, —O—, —S—, ═SO,═SO₂, ═NR^(16B), ═CO, ═PR^(16B) or ═P(O)R^(16B),

where

-   R^(16B)-R^(21B) are identical or different and are each a hydrogen    atom, a halogen atom, a trimethylsilyl group, a C₁-C₁₀-alkyl group,    a C₁-C₁₀-fluoroalkyl group, a C₆-C₁₀-fluoroaryl group, a C₆-C₁₀-aryl    group, a C₁-C₁₀-alkoxy group, a C₇-C₁₅-alkylaryloxy group, a    C₂-C₁₀-alkenyl group, a C₇-C₄₀-arylalkyl group, a C₈-C₄₀-arylalkenyl    group or a C₇-C₄₀-alkylaryl group or two adjacent radicals together    with the atoms connecting them form a saturated or unsaturated ring    having from 4 to 15 carbon atoms, and-   M^(2B)-M^(4B) are each silicon, germanium or tin, or preferably    silicon,-   A^(1B)

—NR^(22B) ₂, PR^(22B) ₂ or an unsubstituted, substituted or fused,heterocyclic ring system, where

-   the radicals R^(22B) are each, independently of one another,    C₁-C₁₀-alkyl, C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl, C₇-C₁₈-alkylaryl or    Si(R^(23B))₃,-   R^(23B) is hydrogen, C₁-C₁₀-alkyl, C₆-C₁₅-aryl which may in turn    bear C₁-C₄-alkyl groups as substituents or C₃-C₁₀-cycloalkyl,-   v is 1 or when A^(1B) is an unsubstituted, substituted or fused,    heterocyclic ring system may also be 0

or where the radicals R^(4B) and R^(12B) together form an—R^(15B)-group.

A^(1B) can, for example together with the bridge R^(15B), form an amine,ether, thioether or phosphine. However, A^(1B) can also be anunsubstituted, substituted or fused, heterocyclic aromatic ring systemwhich can contain heteroatoms from the group consisting of oxygen,sulfur, nitrogen and phosphorus in addition to ring carbons. Examples of5-membered heteroaryl groups which can contain from one to four nitrogenatoms and/or a sulfur or oxygen atom as ring members in addition tocarbon atoms are 2-furyl, 2-thienyl, 2-pyrrolyl, 3-isoxazolyl,5-isoxazolyl, 3-isothiazolyl, 5-isothiazolyl, 1-pyrazolyl, 3-pyrazolyl,5-pyrazolyl, 2-oxazolyl, 4-oxazolyl, 5-oxazolyl, 2-thiazolyl,4-thiazolyl, 5-thiazolyl, 2-imidazolyl, 4-imidazolyl, 5-imidazolyl,1,2,4-oxadiazol-3-yl, 1,2,4-oxa-diazol-5-yl, 1,3,4-oxadiazol-2-yl and1,2,4-triazol-3-yl. Examples of 6-membered heteroaryl groups which maycontain from one to four nitrogen atoms and/or a phosphorus atom are2-pyridinyl, 2-phosphabenzenyl, 3-pyridazinyl, 2-pyrimidinyl,4-pyrimidinyl, 2-pyrazinyl, 1,3,5-triazin-2-yl and 1,2,4-triazin-3-yl,1,2,4-triazin-5-yl and 1,2,4-triazin-6-yl. The 5-membered and 6-memberedheteroaryl groups may also be substituted by C₁-C₁₀-alkyl, C₆-C₁₀-aryl,alkylaryl having from 1 to 10 carbon atoms in the alkyl part and 6-10carbon atoms in the aryl part, trialkylsilyl or halogens such asfluorine, chlorine or bromine or be fused with one or more aromatics orheteroaromatics. Examples of benzo-fused 5-membered heteroaryl groupsare 2-indolyl, 7-indolyl, 2-coumaronyl, 7-coumaronyl, 2-thionaphthenyl,7-thionaphthenyl, 3-indazolyl, 7-indazolyl, 2-benzimidazolyl and7-benzimidazolyl. Examples of benzo-fused 6-membered heteroaryl groupsare 2-quinolyl, 8-quinolyl, 3-cinnolyl, 8-cinnolyl, 1-phthalazyl,2-quinazolyl, 4-quinazolyl, 8-quinazolyl, 5-quinoxalyl, 4-acridyl,1-phenanthridyl and 1-phenazyl. Naming and numbering of the heterocycleshas been taken from L. Fieser and M. Fieser, Lehrbuch der organischenChemie, 3^(rd) revised edition, Verlag Chemie, Weinheim 1957.

The radicals X^(B) in the general formula (I) are preferably identical,preferably fluorine, chlorine, bromine, C₁-C₇-alkyl or aralkyl, inparticular chlorine, methyl or benzyl.

The synthesis of such complexes can be carried out by methods known perse, with the reaction of the appropriately substituted cyclichydrocarbon anions with halides of hafnium being preferred. Examples ofappropriate preparative methods are described, for example, in Journalof Organometallic Chemistry, 369 (1989), 359-370.

The hafnocenes can be used in the Rac or pseudo-Rac form. The termpseudo-Rac refers to complexes in which the two cyclopentadienyl ligandsare in the Rac arrangement relative to one another when all othersubstituents of the complex are disregarded.

Examples of suitable hafnocenes (A) are, inter alia,methylenebis(cyclopentadienyl)hafnium dichloride,methylenebis(3-methylcyclopentadienyl)-hafnium dichloride,methylenebis(3-n-butylcyclopentadienyl)hafnium dichloride,methylene-bis(indenyl)hafnium dichloride,methylenebis(tetrahydroindenyl) hafnium dichloride,isopropylidenebis(cyclopentadienyl)hafnium dichloride,isopropylidenebis(3-trimethylsilylcyclopentadienyl)hafnium dichloride,isopropylidenebis(3-methylcyclopentadienyl)hafnium dichloride,iso-propylidenebis(3-n-butylcyclopentadienyl)hafnium dichloride,isopropylidenebis(3-phenylcyclopentadienyl)hafnium dichloride,isopropylidenebis(indenyl)hafnium dichloride,isopropylidene-bis(tetrahydroindenyl)hafnium dichloride,dimethylsilanediylbis(cyclopentadienyl)hafnium dichloride,dimethylsilanediylbis(indenyl)hafnium dichloride,dimethylsilanediylbis(tetrahydroindenyl)-hafnium dichloride,ethylenebis(cyclopentadienyl)hafnium dichloride,ethylenebis(indenyl)hafnium dichloride,ethylenebis(tetrahydroindenyl)hafnium dichloride,tetramethylethylene-9-fluorenyl-cyclopentadienylhafnium dichloride,dimethylsilanediylbis(tetramethylcyclopentadienyl)hafnium dichloride,dimethylsilanediylbis(3-trimethylsilylcyclopentadienyl)hafniumdichloride, dimethylsilanediylbis(3-methylcyclopentadienyl)hafniumdichloride, dimethylsilanediylbis(3-n-butylcyclopentadienyl)hafniumdichloride,dimethylsilanediylbis(3-tert-butyl-5-methylcyclopentadienyl)-hafniumdichloride,dimethylsilanediylbis(3-tert-butyl-5-ethylcyclopentadienyl)hafniumdichloride, dimethylsilanediylbis(2-methylindenyl)hafnium dichloride,dimethylsilanediylbis(2-isopropylindenyl)hafnium dichloride,dimethylsilanediylbis(2-tert-butylindenyl)hafnium dichloride,diethylsilane-diylbis(2-methylindenyl)hafnium dibromide,dimethylsilanediylbis(3-methyl-5-methylcyclopenta-dienyl)hafniumdichloride,dimethylsilanediylbis(3-ethyl-5-isopropylcyclopentadienyl)hafniumdichloride, dimethylsilanediylbis(2-ethylindenyl)hafnium dichloride,dimethylsilanediylbis(2-methyl-4,5-benzindenyl)hafnium dichloride,dimethylsilanediylbis(2-ethyl-4,5-benzindenyl)hafnium di-chloride,methylphenylsilanediylbis(2-ethyl-4,5-benzindenyl)hafnium dichloride,diphenylsilane-diylbis(2-methyl-4,5-benzindenyl)hafnium dichloride,diphenylsilanediylbis(2-ethyl-4,5-benz-indenyl)hafnium dichloride,diphenylsilanediylbis(2-methylindenyl)hafnium dichloride,dimethylsilanediylbis(2-methyl-4-phenylindenyl)hafnium dichloride,dimethylsilanediylbis(2-ethyl-4-phenylindenyl)hafnium dichloride,dimethylsilanediylbis(2-methyl-4-(1-naphthyl)indenyl)hafnium dichloride,dimethylsilanediylbis(2-ethyl-4-(1-naphthyl)indenyl)hafnium dichloride,dimethylsilane-diylbis(2-propyl-4-(9-phenanthryl)indenyl)hafniumdichloride, dimethylsilanediylbis(2-methyl-4-isopropylindenyl)hafniumdichloride,dimethylsilanediylbis(2,7-dimethyl-4-isopropylindenyl)-hafniumdichloride,dimethylsilanediylbis(2-methyl-4,6-diisopropylindenyl)hafniumdichloride,dimethylsilanediylbis(2-methyl-4[p-trifluoromethylphenyl]indenyl)hafniumdichloride,dimethylsilanediylbis(2-methyl-4-[3′,5′-dimethylphenyl]indenyl)hafniumdichloride,dimethylsilanediylbis(2-methyl-4-[4′-tert-butylphenyl]indenyl)hafniumdichloride,diethylsilanediylbis(2-methyl-4-[4′-tert-butylphenyl]indenyl)hafniumdichloride,dimethylsilanediylbis(2-ethyl-4-[4′-tert-butylphenyl]-indenyl)hafniumdichloride,dimethylsilanediylbis(2-propyl-4[4′-tert-butylphenyl]indenyl)hafniumdichloride,dimethylsilanediylbis(2-isopropyl-4-[4′-tert-butylphenyl]indenyl)hafniumdichloride,dimethylsilanediylbis(2-n-butyl-4-[4′-tert-butylphenyl]indenyl)hafniumdichloride,dimethylsilane-diylbis(2-hexyl-4-[4′-tert-butylphenyl]indenyl)hafniumdichloride,dimethylsilanediyl(2-isopropyl-4-(1-naphthyl)indenyl)(2-methyl-4-(1-naphthyl)indenyl)hafniumdichloride,dimethylsilanediyl(2-isopropyl-4-[4′-tert-butylphenyl]indenyl)(2-methyl-4-[1′-naphthyl]indenyl)hafniumdichloride and ethylene(2-isopropyl-4-[4′-tert-butylphenyl]indenyl)(2-methyl-4-[4′-tert-butylphenyl]indenyl)-hafnium dichloride,and also the corresponding dimethylhafnium,monochloromono(alkylaryloxy)-hafnium and di(alkylaryloxy)hafniumcompounds. The complexes can be used in the rac form, the meso form oras mixtures of these.

Among the hafnocenes of the general formula (I), those of the formula(II)

are preferred.

Among the compounds of the formula (VII), preference is given to thosein which

-   X^(B) is fluorine, chlorine, bromine, C₁-C₄-alkyl or benzyl, or two    radicals X^(B) form a substituted or unsubstituted butadiene ligand,-   t is 1 or 2, preferably 2,-   R^(1B) to R^(5B) are each hydrogen, C₁-C₈-alkyl, C₆-C₈-aryl, NR^(8B)    ₂, OSiR^(8B) ₃ or Si(R^(8B))₃ and-   R^(9B) to R^(13B) are each hydrogen, C₁-C₈-alkyl or C₆-C₈-aryl,    NR^(14B) ₂, OSiR^(14B) ₃ or Si(R^(14B))₃

or in each case two radicals R^(1B) to R^(5B) and/or R^(9B) to R^(13B)together with the C₅ ring form an indenyl, fluorenyl or substitutedindenyl or fluorenyl system.

The hafnocenes of the formula (II) in which the cyclopentadienylradicals are identical are particularly useful.

Examples of particularly suitable compounds (A) of the formula (II) are,inter alia: bis(cyclopentadienyl)hafnium dichloride, bis(indenyl)hafniumdichloride, bis(fluorenyl)hafnium dichloride,bis(tetrahydroindenyl)hafnium dichloride,bis(pentamethylcyclopentadienyl)hafnium dichloride,bis(trimethylsilylcyclopentadienyl)hafnium dichloride,bis(trimethoxysilylcyclopentadienyl)hafnium dichloride,bis(ethylcyclopentadienyl)hafnium dichloride,bis(isobutylcyclopentadienyl)hafnium dichloride,bis(3-butenylcyclopentadienyl)hafnium dichloride,bis(methylcyclopentadienyl)hafnium dichloride,bis(1,3-di-tert-butylcyclopentadienyl)hafnium dichloride,bis(trifluoromethylcyclopentadienyl)hafnium dichloride,bis(tert-butylcyclopentadienyl)hafnium dichloride,bis(n-butylcyclopentadienyl)hafnium dichloride,bis(phenylcyclopentadienyl)hafnium dichloride,bis(N,N-dimethylaminomethylcyclopentadienyl)hafnium dichloride,bis(1,3-dimethyl-cyclopentadienyl)hafnium dichloride,bis(1-n-butyl-3-methylcyclopentadienyl)hafnium dichloride,(cyclopentadienyl)(methylcyclopentadienyl)hafnium dichloride,(cyclopentadienyl)(n-butylcyclopentadienyl)hafnium dichloride,(methylcyclopentadienyl)(n-butylcyclopentadienyl)hafnium dichloride,(cyclopentadienyl)(1-methyl-3-n-butylcyclopentadienyl)hafniumdichloride, bis(tetra-methylcyclopentadienyl)hafnium dichloride and alsothe corresponding dimethylhafnium compounds.

Further examples are the corresponding hafnocene compounds in which oneor two of the chloride ligands have been replaced by bromide or iodide.

Suitable catalysts B) are transition metal complexes with at least oneligand of the general formulae (III),

where the variables have the following meanings:

-   E^(1C) is nitrogen or phosphorus, in particular nitrogen,-   E^(2C)-E^(4C) are each, independently of one another, carbon,    nitrogen or phosphorus, in particular carbon,-   R^(1C)-R^(3C) are each, independently of one another, hydrogen    C₁-C₂₂-alkyl, C₂-C₂₂-alkenyl, C₆-C₂₂-aryl, alkylaryl having from 1    to 10 carbon atoms in the alkyl part and 6-20 carbon atoms in the    aryl part, halogen, NR^(18C) ₂, OR^(18C), SiR^(19C) ₃, where the    organic radicals R^(1C)-R^(3C) may also be substituted by halogens    and/or two vicinal radicals R^(1C)-R^(3C) may also be joined to form    a five-, six- or seven-membered ring, and/or two vicinal radicals    R^(1C)-R^(3C) are joined to form a five-, six- or seven-membered    heterocycle containing at least one atom from the group consisting    of N, P, O and S,-   R^(4C)-R^(7C) are each, independently of one another, hydrogen,    C₁-C₂₂-alkyl, C₂-C₂₂-alkenyl, C₆-C₂₂-aryl, alkylaryl having from 1    to 10 carbon atoms in the alkyl part and 6-20 carbon atoms in the    aryl part, NR^(18C) ₂, SiR^(19C) ₃, where the organic radicals    R^(4C)-R^(7C) may also be substituted by halogens and/or two geminal    or vicinal radicals R^(4C)-R^(7C) may also be joined to form a    five-, six- or seven-membered ring, and/or two geminal or vicinal    radicals R^(4C)-R^(9C) are joined to form a five-, six- or    seven-membered heterocycle containing at least one atom from the    group consisting of N, P, O and S, and when v is O, R^(6C) is a bond    to L^(1C) and/or R^(7C) is a bond to L^(2C) so that L^(1C) forms a    double bond to the carbon atom bearing R^(4C) and/or L^(2C) forms a    double bond to the carbon atom bearing R^(5C),-   u is 0 when E^(2C)-E^(4C) is nitrogen or phosphorus and is 1 when    E^(2C)-E^(4C) is carbon,-   L^(1C)-L^(2C) are each, independently of one another, nitrogen or    phosphorus, in particular nitrogen,-   R^(8C)-R^(11C) are each, independently of one another, hydrogen,    C₁-C₂₂-alkyl, C₂-C₂₂-alkenyl, C₆-C₂₂-aryl, alkylaryl having from 1    to 10 carbon atoms in the alkyl part and 6-20 carbon atoms in the    aryl part, halogen, NR^(18C) ₂, OR^(18C), SiR^(19C) ₃, where the    organic radicals R^(8C)-R^(11C) may also be substituted by halogens    and/or two vicinal radicals R^(8C)-R^(17C) may also be joined to    form a five-, six- or seven-membered ring, and/or two vicinal    radicals R^(8C)-R^(17C) are joined to form a five-, six- or    seven-membered heterocycle containing at least one atom from the    group consisting of N, P, O and S, and with the proviso that at    least R^(8C) and R^(10C) are halogen or a tert. C₁-C₂₂-alkyl group,-   R^(12C)-R^(17C) are each, independently of one another, hydrogen,    C₁-C₂₂-alkyl, C₂-C₂₂-alkenyl, C₆-C₂₂-aryl, alkylaryl having from 1    to 10 carbon atoms in the alkyl part and 6-20 carbon atoms in the    aryl part, halogen, NR^(18C) ₂, OR^(18C), SiR^(19C) ₃, where the    organic radicals R^(12C)-R^(17C) may also be substituted by halogens    and/or two vicinal radicals R^(8C)-R^(17C) may also be joined to    form a five-, six- or seven-membered ring, and/or two vicinal    radicals R^(8C)-R^(17C) are joined to form a five-, six- or    seven-membered heterocycle containing at least one atom from the    group consisting of N, P, O and S,-   the indices v are each, independently of one another, 0 or 1,-   the radicals X^(C) are each, independently of one another, fluorine,    chlorine, bromine, iodine, hydrogen, C₁-C₁₀-alkyl, C₂-C₁₀-alkenyl,    C₆-C₂₀-aryl, alkylaryl having 1-10 carbon atoms in the alkyl part    and 6-20 carbon atoms in the aryl part, NR^(18C) ₂, OR^(18C),    SR^(18C), SO₃R^(18C), OC(O)R^(18C), CN, SCN, β-diketonate, CO, BF₄    ⁻, PF₆ ⁻ or a bulky noncoordinating anion and the radicals X^(C) may    be joined to one another,-   the radicals R^(18C) are each, independently of one another,    hydrogen, C₁-C₂₀-alkyl, C₂-C₂₀-alkenyl, C₆-C₂₀-aryl, alkylaryl    having from 1 to 10 carbon atoms in the alkyl part and 6-20 carbon    atoms in the aryl part, SiR^(19C) ₃, where the organic radicals    R^(18C) may also be substituted by halogens or nitrogen- and    oxygen-containing groups and two radicals R^(18C) may also be joined    to form a five- or six-membered ring,-   the radicals R^(19C) are each, independently of one another,    hydrogen, C₁-C₂₀-alkyl, C₂-C₂₀-alkenyl, C₆-C₂₀-aryl, alkylaryl    having from 1 to 10 carbon atoms in the alkyl part and 6-20 carbon    atoms in the aryl part, where the organic radicals R^(19C) may also    be substituted by halogens or nitrogen- and oxygen-containing groups    and two radicals R^(19C) may also be joined to form a five- or    six-membered ring,-   s is 1, 2, 3 or 4, in particular 2 or 3,-   D is an uncharged donor and-   t is from 0 to 4, in particular 0, 1 or 2.

The three atoms E^(2C) to E^(4C) in a molecule can be identical ordifferent. If E^(1C) is phosphorus, then E^(2C) to E^(4C) are preferablyeach carbon. If E^(1C) is nitrogen, then E^(2C) to E^(4C) are eachpreferably nitrogen or carbon, in particular carbon.

The substituents R^(1C)-R^(3C) and R^(8C)-R^(17C) can be varied within awide range. Possible carboorganic substituents R^(1C)-R^(3C) andR^(8C)-R^(17C) are, for example, the following: C₁-C₂₂-alkyl which maybe linear or branched, e.g. methyl, ethyl, n-propyl, isopropyl, n-butyl,isobutyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl,n-decyl or n-dodecyl, 5- to 7-membered cycloalkyl which may in turn beara C₁-C₁₀-alkyl group and/or C₆-C₁₀-aryl group as substituents, e.g.cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl,cyclooctyl, cyclononyl or cyclododecyl, C₂-C₂₂-alkenyl which may belinear, cyclic or branched and in which the double bond may be internalor terminal, e.g. vinyl, 1-allyl, 2-allyl, 3-allyl, butenyl, pentenyl,hexenyl, cyclopentenyl, cyclohexenyl, cyclooctenyl or cyclooctadienyl,C₆-C₂₂-aryl which may be substituted by further alkyl groups, e.g.phenyl, naphthyl, biphenyl, anthranyl, o-, m-, p-methylphenyl, 2,3-,2,4-, 2,5- or 2,6-dimethylphenyl, 2,3,4-, 2,3,5-, 2,3,6-, 2,4,5-, 2,4,6-or 3,4,5-trimethylphenyl, or arylalkyl which may be substituted byfurther alkyl groups, e.g. benzyl, o-, m-, p-methylbenzyl, 1- or2-ethylphenyl, where two radicals R^(1C) to R^(3C) and/or two vicinalradicals R^(8C)-R^(17C) may also be joined to form a 5-, 6- or7-membered ring and/or two of the vicinal radicals R^(1C)-R^(3C) and/ortwo of the vicinal radicals R^(8C)-R^(17C) may be joined to form afive-, six- or seven-membered heterocycle containing at least one atomfrom the group consisting of N, P, O and S and/or the organic radicalsR^(1C)-R^(3C) and/or R^(8C)-R^(17C) may also be substituted by halogenssuch as fluorine, chlorine or bromine. Furthermore, R^(1C)-R^(3C) andR^(8C)-R^(17C) can also be amino NR^(18C) ₂ or N(SiR^(19C) ₃)₂, alkoxyor aryloxy OR^(18C), for example dimethylamino, N-pyrrolidinyl,picolinyl, methoxy, ethoxy or isopropoxy or halogen such as fluorine,chlorine or bromine. Possible radicals R^(19C) in organosiliconsubstituents SiR^(19C) ₃ are the same carboorganic radicals as have beendescribed above for R^(1C)-R^(3C), where two R^(19C) may also be joinedto form a 5- or 6-membered ring, e.g. trimethylsilyl, triethylsilyl,butyldimethylsilyl, tributylsilyl, tri-tert-butylsilyl, triallylsilyl,triphenylsilyl or dimethylphenylsilyl. These SiR^(19C) ₃ radicals mayalso be bound to E^(2C)-E^(4C) via an oxygen or nitrogen, for exampletrimethylsilyloxy, triethyl-silyloxy, butyldimethylsilyloxy,tributylsilyloxy or tri-tert-butylsilyloxy.

Preferred radicals R^(1C)-R^(3C) are hydrogen, methyl, trifluoromethyl,ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl,n-hexyl, n-heptyl, n-octyl, vinyl, allyl, benzyl, phenyl, ortho-dialkyl-or -dichloro-substituted phenyls, trialkyl- or trichloro-substitutedphenyls, naphthyl, biphenyl and anthranyl. Particularly preferredorganosilicon substituents are trialkylsilyl groups having from 1 to 10carbon atoms in the alkyl radical, in particular trimethylsilyl groups.

Preferred radicals R^(12C)-R^(17C) are hydrogen, methyl,trifluoromethyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl,tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, vinyl, allyl, benzyl,phenyl, fluorine, chlorine and bromine, in particular hydrogen. Inparticular, R^(13C) and R^(16C) are each methyl, trifluoromethyl, ethyl,n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl,n-heptyl, n-octyl, vinyl, allyl, benzyl, phenyl, fluorine, chlorine orbromine and R^(12C), R^(14C), R^(15C) and R^(17C) are each hydrogen.

Preferred radicals R^(9C) and R^(11C) are hydrogen, methyl,trifluoromethyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl,tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, vinyl, allyl, benzyl,phenyl, fluorine, chlorine and bromine. In particular, R^(8C) andR^(10C) are preferably a halogen such as fluorine, chlorine or bromine,particularly chlorine and R^(9C) and R^(11C) are each a C₁-C₂₂-alkylwhich may also be substituted by halogens, in particular aC₁-C₂₂-n-alkyl which may also be substituted by halogens, e.g. methyl,trifluoromethyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl,n-octyl, vinyl, or a halogen such as fluorine, chlorine or bromine. Inanother preferred combination R^(8C) and R^(10C) are a tertiaryC₁-C₂₂-alkyl radical, particularly tert. butyl and R^(9C) and R^(11C)are each hydrogen or a halogen such as fluorine, chlorine or bromine.

In particular, R^(12C), R^(14C), R^(15C) and R^(17C) are identical,R^(13C) and R^(16C) are identical, R^(9C) and R^(11C) are identical andR^(8C) and R^(10C) are identical. This is also preferred in thepreferred embodiments described above.

The substituents R^(4C)-R^(7C), too, can be varied within a wide range.Possible carboorganic substituents R^(4C)-R^(7C) are, for example, thefollowing: C₁-C₂₂-alkyl which may be linear or branched, e.g. methyl,ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl,n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl or n-dodecyl, 5- to7-membered cycloalkyl which may in turn bear a C₁-C₁₀-alkyl group and/orC₆-C₁₀-aryl group as substituent, e.g. cyclopropyl, cyclobutyl,cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl orcyclododecyl, C₂-C₂₂-alkenyl which may be linear, cyclic or branched andin which the double bond may be internal or terminal, e.g. vinyl,1-allyl, 2-allyl, 3-allyl, butenyl, pentenyl, hexenyl, cyclopentenyl,cyclohexenyl, cyclooctenyl or cyclooctadienyl, C₆-C₂₂-aryl which may besubstituted by further alkyl groups, e.g. phenyl, naphthyl, biphenyl,anthranyl, o-, m-, p-methylphenyl, 2,3-, 2,4-, 2,5- or2,6-dimethylphenyl, 2,3,4-, 2,3,5-, 2,3,6-, 2,4,5-, 2,4,6- or3,4,5-trimethylphenyl, or arylalkyl, where the arylalkyl may besubstituted by further alkyl groups, e.g. benzyl, o-, m-,p-methylbenzyl, 1- or 2-ethylphenyl, where two radicals R^(4C) to R^(7C)may also be joined to form a 5-, 6- or 7-membered ring and/or twogeminal radicals R^(4C)-R^(7C) may be joined to form a five-, six- orseven-membered heterocycle containing at least one atom from the groupconsisting of N, P, O and S and/or the organic radicals R^(4C)-R^(7C)may also be substituted by halogens such as fluorine, chlorine orbromine. Furthermore, R^(4C)-R^(7C) may be amino NR^(18C) ₂ orN(SiR^(19C) ₃)₂, for example dimethylamino, N-pyrrolidinyl or picolinyl.Possible radicals R^(19C) in organosilicone substituents SiR^(19C) ₃ arethe same carboorganic radicals as have been described above forR^(1C)-R^(3C), where two R^(19C) may also be joined to form a 5- or6-membered ring, e.g. trimethylsilyl, triethylsilyl, butyldimethylsilyl,tributylsilyl, tri-tert-butylsilyl, triallylsilyl, triphenylsilyl ordimethylphenylsilyl. These SiR^(19C) ₃ radicals can also be bound vianitrogen to the carbon bearing them. When v is 0, R^(6C) is a bond toL^(C) and/or R^(7C) is a bond to L^(2C), so that L^(1C) forms a doublebond to the carbon atom bearing R^(4C) and/or L^(2C) forms a double bondto the carbon atom bearing R^(5C).

Preferred radicals R^(4C)-R^(7C) are hydrogen, methyl, ethyl, n-propyl,isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl,n-octyl, benzyl, phenyl, ortho-dialkyl- or dichloro-substituted phenyls,trialkyl- or trichloro-substituted phenyls, naphthyl, biphenyl andanthranyl. Preference is also given to amide substituents NR^(18C) ₂, inparticular secondary amides such as dimethylamide, N-ethylmethylamide,diethylamide, N-methylpropylamide, N-methylisopropylamide,N-ethyliso-propylamide, dipropylamide, diisopropylamide,N-methylbutylamide, N-ethylbutylamide, N-methyl-tert-butylamide,N-tert-butylisopropylamide, dibutylamide, di-sec-butylamide,diisobutylamide, tert-amyl-tert-butylamide, dipentylamide,N-methylhexylamide, dihexylamide, tert-amyl-tert-octylamide,dioctylamide, bis(2-ethylhexyl)amide, didecylamide,N-methyloctadecylamide, N-methylcyclohexylamide, N-ethylcyclohexylamide,N-isopropylcyclohexylamide, N-tert-butyl-cyclohexylamide,dicyclohexylamide, pyrrolidine, piperidine, hexamethylenimine,decahydro-quinoline, diphenylamine, N-methylanilide or N-ethylanilide.

L^(1C) and L^(2C) are each, independently of one another, nitrogen orphosphorus, in particular nitrogen, and when v is 0 can form a doublebond with the carbon atom bearing R^(4C) or R^(5C). In particular, whenv is 0, L^(1C) and/or L^(2C) together with the carbon atom bearingR^(4C) or R^(5C) form an imino group —CR^(4C)═N— or —CR^(5C)═N—. When vis 1, L^(1C) and/or L^(2C) together with the carbon atom bearing R^(4C)or R^(5C) forms, in particular, an amido group —CR^(4C)R^(6C)—N⁻— or—CR^(5C)R^(7C)—N⁻—.

The ligands X^(C) result, for example, from the choice of theappropriate starting metal compounds used for the synthesis of the ironcomplexes, but can also be varied afterward. Possible ligands X^(C) are,in particular, the halogens such as fluorine, chlorine, bromine oriodine, in particular chlorine. Alkyl radicals such as methyl, ethyl,propyl, butyl, vinyl, allyl, phenyl or benzyl are also usable ligandsX^(C). As further ligands X^(C), mention may be made, purely by way ofexample and in no way exhaustively, of trifluoroacetate, BF₄ ⁻, PF₆ ⁻and weakly coordinating or noncoordinating anions (cf., for example, S.Strauss in Chem. Rev. 1993, 93, 927-942), e.g. B(C₆F₆)₄ ⁻. Amides,alkoxides, sulfonates, carboxylates and β-diketonates are alsoparticularly useful ligands X^(C). Some of these substituted ligands Xare particularly preferably used since they are obtainable from cheapand readily available starting materials. Thus, a particularly preferredembodiment is that in which X^(C) is dimethylamide, methoxide, ethoxide,isopropoxide, phenoxide, naphthoxide, triflate, p-toluenesulfonate,acetate or acetylacetonate.

Variation of the radicals R^(18C) enables, for example, physicalproperties such as solubility to be finely adjusted. Possiblecarboorganic substituents R^(18C) are, for example, the following:C₁-C₂₀-alkyl which may be linear or branched, e.g. methyl, ethyl,n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl,n-heptyl, n-octyl, n-nonyl, n-decyl or n-dodecyl, 5- to 7-memberedcycloalkyl which may in turn bear a C₆-C₁₀-aryl group as substituent,e.g. cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl,cyclooctyl, cyclononyl or cyclododecyl, C₂-C₂₀-alkenyl which may belinear, cyclic or branched and in which the double bond may be internalor terminal, e.g. vinyl, 1-allyl, 2-allyl, 3-allyl, butenyl, pentenyl,hexenyl, cyclopentenyl, cyclohexenyl, cyclooctenyl or cyclooctadienyl,C₆-C₂₀-aryl which may be substituted by further alkyl groups and/or N-or O-containing radicals, e.g. phenyl, naphthyl, biphenyl, anthranyl,o-, m-, p-methylphenyl, 2,3-, 2,4-, 2,5- or 2,6-dimethylphenyl, 2,3,4-,2,3,5-, 2,3,6-, 2,4,5-, 2,4,6- or 3,4,5-trimethylphenyl,2-methoxyphenyl, 2-N,N-dimethylaminophenyl, or arylalkyl which may besubstituted by further alkyl groups, e.g. benzyl, o-, m-,p-methylbenzyl, 1- or 2-ethylphenyl, where two radicals R^(18C) may alsobe joined to form a 5- or 6-membered ring and the organic radicalsR^(18C) may also be substituted by halogens such as fluorine, chlorineor bromine. Possible radicals R^(19C) in organosilicon substituentsSiR^(19C) ₃ are the same radicals which have been described above forR^(18C), where two radicals R^(19C) may also be joined to form a 5- or6-membered ring, e.g. trimethylsilyl, triethylsilyl, butyldimethylsilyl,tributylsilyl, triallylsilyl, triphenylsilyl or dimethylphenyl-silyl.Preference is given to using C₁-C₁₀-alkyl such as methyl, ethyl,n-propyl, n-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, andalso vinyl allyl, benzyl and phenyl as radicals R^(18C).

The number s of the ligands X^(C) depends on the oxidation state of theiron. The number s can thus not be given in general terms. The oxidationstate of the iron in catalytically active complexes is usually known tothose skilled in the art. However, it is also possible to use complexeswhose oxidation state does not correspond to that of the activecatalyst. Such complexes can then be appropriately reduced or oxidizedby means of suitable activators. Preference is given to using ironcomplexes in the oxidation state +3 or +2.

D is an uncharged donor, in particular an uncharged Lewis base or Lewisacid, for example amines, alcohols, ethers, ketones, aldehydes, esters,sulfides or phosphines which may be bound to the iron center or elsestill be present as residual solvent from the preparation of the ironcomplexes.

The number t of the ligands D can be from 0 to 4 and is often dependenton the solvent in which the iron complex is prepared and the time forwhich the resulting complexes are dried and can therefore also be anonintegral number such as 0.5 or 1.5. In particular, t is 0, 1 to 2.

In a preferred embodiment the complexes (B) are of formula (IV)

where

-   E^(2C)-E^(4C) are each, independently of one another, carbon,    nitrogen or phosphorus, in particular carbon,-   R^(1C)-R^(3C) are each, independently of one another, hydrogen,    C₁-C₂₂-alkyl, C₂-C₂₂-alkenyl, C₆-C₂₂-aryl, alkylaryl having from 1    to 10 carbon atoms in the alkyl part and 6-20 carbon atoms in the    aryl part, halogen, NR^(18C) ₂, OR^(18C), SiR^(19C) ₃, where the    organic radicals R^(1C)-R^(3C) may also be substituted by halogens    and/or two vicinal radicals R^(1C)-R^(3C) may also be joined to form    a five-, six- or seven-membered ring, and/or two vicinal radicals    R^(1C)-R^(3C) are bound to form a five-, six- or seven-membered    heterocycle containing at least one atom from the group consisting    of N, P, O and S,-   R^(4C)-R^(5C) are each, independently of one another, hydrogen,    C₁-C₂₂-alkyl, C₂-C₂₂-alkenyl, C₆-C₂₂-aryl, alkylaryl having from 1    to 10 carbon atoms in the alkyl part and 6-20 carbon atoms in the    aryl part, NR^(18C) ₂, SiR^(19C) ₃, where the organic radicals    R^(4C)-R^(5C) may also be substituted by halogens,-   u is 0 when E^(2C)-E^(4C) is nitrogen or phosphorus and is 1 when    E^(2C)-E^(4C) is carbon,-   L^(1C)-L^(12C) are each, independently of one another, nitrogen or    phosphorus, in particular nitrogen,-   R^(8C)-R^(11C) are each, independently of one another, C₁-C₂₂-alkyl,    C₂-C₂₂-alkenyl, C₆-C₂₂-aryl, alkylaryl having from 1 to 10 carbon    atoms in the alkyl part and 6-20 carbon atoms in the aryl part,    halogen, NR^(18C) ₂, OR^(18C), SiR^(19C) ₃, where the organic    radicals R^(8C)-R^(11C) may also be substituted by halogens and/or    two vicinal radicals R^(8C)-R^(17C) may also be joined to form a    five-, six- or seven-membered ring, and/or two vicinal radicals    R^(8C)-R^(17C) are joined to form a five-, six- or seven-membered    heterocycle containing at least one atom from the group consisting    of N, P, O and S, and with the proviso that at least R^(8C) and    R^(10C) are halogen or a tert. C₁-C₂₂-alkyl group,-   R^(12C)-R^(17C) are each, independently of one another, hydrogen,    C₁-C₂₂-alkyl, C₂-C₂₂-alkenyl, C₆-C₂₂-aryl, alkylaryl having from 1    to 10 carbon atoms in the alkyl part and 6-20 carbon atoms in the    aryl part, halogen, NR^(18C) ₂, OR^(18C), SiR^(19C) ₃, where the    organic radicals R^(12C)-R^(17C) may also be substituted by halogens    and/or two vicinal radicals R^(8C)-R^(17C) may also be joined to    form a five-, six- or seven-membered ring, and/or two vicinal    radicals R^(8C)-R^(17C) are joined to form a five-, six- or    seven-membered heterocycle containing at least one atom from the    group consisting of N, P, O or S,-   the indices v are each, independently of one another, 0 or 1,-   the radicals X^(C) are each, independently of one another, fluorine,    chlorine, bromine, iodine, hydrogen, C₁-C₁₀-alkyl, C₂-C₁₀-alkenyl,    C₆-C₂₀-aryl, alkylaryl having 1-10 carbon atoms in the alkyl part    and 6-20 carbon atoms in the aryl part, NR^(18C) ₂, OR^(18C),    OR^(18C), SO₃R^(18C), OC(O)R^(18C), CN, SCN, β-diketonate, CO, BF₄    ⁻, PF₆ ⁻ or a bulky noncoordinating anion and the radicals X^(C) may    be joined to one another,-   the radicals R^(18C) are each, independently of one another,    hydrogen, C₁-C₂₀-alkyl, C₂-C₂₀-alkenyl, C₆-C₂₀-aryl, alkylaryl    having from 1 to 10 carbon atoms in the alkyl part and 6-20 carbon    atoms in the aryl part, SiR^(19C) ₃, where the organic radicals    R^(18C) may also be substituted by halogens and nitrogen- and    oxygen-containing groups and two radicals R^(18C) may also be joined    to form a five- or six-membered ring,-   the radicals R^(19C) are each, independently of one another,    hydrogen, C₁-C₂₀-alkyl, C₂-C₂₀-alkenyl, C₆-C₂₀-aryl, alkylaryl    having from 1 to 10 carbon atoms in the alkyl part and 6-20 carbon    atoms in the aryl part, where the organic radicals R^(19C) may also    be substituted by halogens or nitrogen- and oxygen-containing groups    and two radicals R^(19C) may also be joined to form a five- or    six-membered ring,-   s is 1, 2, 3 or 4, in particular 2 or 3,-   D is an uncharged donor and-   t is from 0 to 4, in particular 0, 1 or 2.

The embodiments and preferred embodiments described above likewise applyto E^(2C)-E^(4C), R^(1C)-R^(3C), X^(C), R^(18C) and R^(19C).

The substituents R^(4C)-R^(5C) can be varied within a wide range.Possible carboorganic substituents R^(4C)-R^(5C) are, for example, thefollowing: hydrogen, C₁-C₂₂-alkyl which may be linear or branched, e.g.methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl,n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl or n-dodecyl, 5-to 7-membered cycloalkyl which may in turn bear a C₁-C₁₀-alkyl groupand/or C₆-C₁₀-aryl group as substituent, e.g. cyclopropyl, cyclobutyl,cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl orcyclododecyl, C₂-C₂₂-alkenyl which may be linear, cyclic or branched andin which the double bond may be internal or terminal, e.g. vinyl,1-allyl, 2-allyl, 3-allyl, butenyl, pentenyl, hexenyl, cyclopentenyl,cyclohexenyl, cyclooctenyl or cyclooctadienyl, C₆-C₂₂-aryl which may besubstituted by further alkyl groups, e.g. phenyl, naphthyl, biphenyl,anthranyl, o-, m-, p-methylphenyl, 2,3-, 2,4-, 2,5- or2,6-dimethylphenyl, 2,3,4-, 2,3,5-, 2,3,6-, 2,4,5-, 2,4,6- or3,4,5-trimethylphenyl, or arylalkyl which may be substituted by furtheralkyl groups, e.g. benzyl, o-, m-, p-methylbenzyl, 1- or 2-ethylphenyl,where the organic radicals R^(4C)-R^(5C) may also be substituted byhalogens such as fluorine, chlorine or bromine. Furthermore,R^(4C)-R^(5C) can be amino NR^(18C) ₂ or N(SiR^(19C) ₃)₂, for exampledimethylamino, N-pyrrolidinyl or picolinyl. Possible radicals R^(19C) inorganosilicon substituents SiR^(19C) ₃ are the same carboorganicradicals as described above for R^(1C)-R^(3C), where two radicalsR^(19C) may also be joined to form a 5- or 6-membered ring, e.g.trimethylsilyl, triethylsilyl, butyldimethylsilyl, tributylsilyl,tritert-butylsilyl, triallylsilyl, triphenylsilyl ordimethylphenylsilyl. These SiR^(19C) ₃ radicals can also be bound vianitrogen to the carbon bearing them.

Preferred radicals R^(4C)-R^(5C) are hydrogen, methyl, ethyl, n-propyl,isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl,n-octyl or benzyl, in particular methyl.

The substituents R^(8C)-R^(17C) can be varied within a wide range.Possible carboorganic substituents R^(8C)-R^(17C) are, for example, thefollowing: C₁-C₂₂-alkyl which may be linear or branched, e.g. methyl,ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl,n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl or n-dodecyl, 5- to7-membered cycloalkyl which may in turn bear a C₁-C₁₀-alkyl group and/orC₆-C₁₀-aryl group as substituent, e.g. cyclopropyl, cyclobutyl,cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl orcyclododecyl, C₂-C₂₂-alkenyl which may be linear, cyclic or branched andin which the double may be internal or terminal, e.g. vinyl, 1-allyl,2-allyl, 3-allyl, butenyl, pentenyl, hexenyl, cyclopentenyl,cyclohexenyl, cyclooctenyl or cyclooctadienyl, C₆-C₂₂-aryl which may besubstituted by further alkyl groups, e.g. phenyl, naphthyl, biphenyl,anthranyl, o-, m-, p-methylphenyl, 2,3-, 2,4-, 2,5- or2,6-dimethylphenyl, 2,3,4-, 2,3,5-, 2,3,6-, 2,4,5-, 2,4,6- or3,4,5-trimethylphenyl, or arylalkyl which may be substituted by furtheralkyl groups, e.g. benzyl, o-, m-, p-methylbenzyl, 1- or 2-ethylphenyl,where two radicals R^(8C) to R^(17C) may also be joined to form a 5-, 6-or 7-membered ring and/or two of the vicinal radicals R^(8C)-R^(17C) maybe joined to form a five-, six- or seven-membered heterocycle containingat least one atom from the group consisting of N, P, O and S and/or theorganic radicals R^(8C)-R^(17C) may also be substituted by halogens suchas fluorine, chlorine or bromine. Furthermore, R^(8C)-R^(17C) can behalogen such as fluorine, chlorine, bromine, amino NR^(18C) ₂ orN(SiR^(19X) ₃)₂, alkoxy or aryloxy OR^(18C), for example dimethylamino,N-pyrrolidinyl, picolinyl, methoxy, ethoxy or isopropoxy. Possibleradicals R^(19C) in organosilicon substituents SiR^(19C) ₃ are the samecarboorganic radicals which have been mentioned above for R^(1C)-R^(3C),where two radicals R^(19C) may also be joined to form a 5- or 6-memberedring, e.g. trimethylsilyl, triethylsilyl, butyldimethylsilyl,tributylsilyl, tritert-butylsilyl, triallylsilyl, triphenylsilyl ordimethylphenylsilyl. These SiR^(19C) ₃ radicals can also be bound via anoxygen or nitrogen, for example trimethylsilyloxy, triethylsilyloxy,butyldimethylsilyloxy, tributylsilyloxy or tritert-butylsilyloxy.

Preferred radicals R^(12C)-R^(17C) are hydrogen, methyl,trifluoromethyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl,tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, vinyl, allyl, benzyl,phenyl, fluorine, chlorine and bromine, in particular hydrogen. Inparticular, R^(13C) and R^(16C) are each methyl, trifluoromethyl, ethyl,n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl,n-heptyl, n-octyl, vinyl, allyl, benzyl, phenyl, fluorine, chlorine orbromine and R^(12C), R^(14C), R^(15C) and R^(17C) are each hydrogen.

Preferred radicals R^(9C) and R^(11C) are hydrogen, methyl,trifluoromethyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl,tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, vinyl, allyl, benzyl,phenyl, fluorine, chlorine and bromine. In particular, R^(8C) andR^(10C) are preferably a halogen such as fluorine, chlorine or bromine,particularly chlorine and R^(9C) and R^(11C) are each a C₁-C₂₂-alkylwhich may also be substituted by halogens, in particular aC₁-C₂₂-n-alkyl which may also be substituted by halogens, e.g. methyl,trifluoromethyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl,n-octyl, vinyl, or a halogen such as fluorine, chlorine or bromine. Inanother preferred combination R^(8C) and R^(10C) are a tertiaryC₁-C₂₂-alkyl radical, particularly tert. butyl and R^(9C) and R^(11C)are each hydrogen or a halogen such as fluorine, chlorine or bromine.

In particular, R^(12C), R^(14C), R^(15C) and R^(17C) are identical,R^(13C) and R^(16C) are identical, R^(9C) and R^(11C) are identical andR^(8C) and R^(10C) are identical. This is also preferred in thepreferred embodiments described above.

The preparation of the compounds B) is described, for example, in J. Am.Chem. Soc. 120, p. 4049 ff. (1998), J. Chem. Soc., Chem. Commun. 1998,849, and WO 98/27124. Preferred complexes B) are2,6-Bis[1-(2-tert.butylphenylimino)ethyl]pyridine iron(II) dichloride,2,6-Bis[1-(2-tert.butyl-6-chlorophenylimino)ethyl]pyridine iron(II)dichloride, 2,6-Bis[1-(2-chloro-6-methyl-phenylimino)ethyl]pyridineiron(II) dichloride, 2,6-Bis[1-(2,4-dichlorophenylimino)ethyl]pyridineiron(II) dichloride, 2,6-Bis[1-(2,6-dichlorophenylimino)ethyl]pyridineiron(II) dichloride, 2,6-Bis[1-(2,4-dichlorophenylimino)methyl]pyridineiron(II) dichloride,2,6-Bis[1-(2,4-dichloro-6-methyl-phenylimino)ethyl]pyridine iron(II)dichloride-2,6-Bis[1-(2,4-difluorophenylimino)ethyl]pyridine iron(II)dichloride, 2,6-Bis[1-(2,4-dibromophenylimino)ethyl]pyridine iron(II)dichloride or the respective trichlorides, dibromides or tribromides.

In the following, reference to a transition metal complex (A) orcatalyst (A) means a hafnocene (A). The molar ratio of transition metalcomplex A) to polymerization catalyst B) is usually in the range from1:100 to 100:1, preferably from 1:10 to 10:1 and particularly preferablyfrom 1:1 to 5:1. When a transition metal complex A) is used as solecatalyst under the same reaction conditions in the homopolymerization orcopolymerization of ethylene, it preferably produces a higher Mw thandoes the complex (B) when it is used as sole complex under the samereaction conditions. The preferred embodiments of the complexes (A) and(B) are likewise preferred in combinations of the two complexes.

When a transition metal complex A) is used as sole catalyst under thesame reaction conditions in the homopolymerization or copolymerizationof ethylene, it preferably produces a higher Mw than does the complex(B) when it is used as sole complex under the same reaction conditions.

The catalyst composition of the invention can be used alone or togetherwith further components as catalyst system for olefin polymerization.Furthermore, we have found catalyst systems for olefin polymerizationcomprising

-   A) at least one polymerization catalyst based on a hafnocene (A),-   B) at least one polymerization catalyst based on an iron component    having a tridentate ligand bearing at least two aryl radicals with    each bearing a halogen or tert. alkyl substituent in the    ortho-position,-   C) optionally one or more activating compounds,-   D) optionally one or more organic or inorganic supports,-   E) optionally one or more metal compounds of a metal of group 1, 2    or 13 of the Periodic Table.

The hafnocene (A) and/or the iron complex (B) sometimes have only a lowpolymerization activity and are then brought into contact with one ormore activators, viz. the component (C), in order to be able to displaya good polymerization activity. The catalyst system therefore optionallyfurther comprises, as component (C) one or more activating compounds,preferably one or two activating compounds (C). The catalyst system ofthe invention preferably comprises one or more activators (C). Dependingon the catalyst combinations (A) and (B), one or more activatingcompounds (C) are advantageous. The activation of the transition metalcomplex (A) and of the iron complex (B) of the catalyst composition canbe carried out using the same activator or activator mixture ordifferent activators. It is often advantageous to use the same activator(C) for both the catalysts (A) and (B).

The activator or activators (C) can in each case be used in any amountsbased on the complexes (A) and (B) of the catalyst composition of theinvention. They are preferably used in an excess or in stoichiometricamounts, in each case based on the complex (A) or (B) which theyactivate. The amount of activating compound(s) to be used depends on thetype of the activator (C). In general, the molar ratio of transitionmetal complex (A) to activating compound (C) can be from 1:0.1 to1:10000, preferably from 1:1 to 1:2000. The molar ratio of iron complex(B) to activating compound (C) is also usually in the range from 1:0.1to 1:10000, preferably from 1:1 to 1:2000.

Suitable compounds (C) which are able to react with the transition metalcomplex (A) or the iron complex (B) to convert it into a catalyticallyactive or more active compound are, for example, compounds such as analuminoxane, a strong uncharged Lewis acid, an ionic compound having aLewis-acid cation or an ionic compound containing a Brönsted acid ascation.

As aluminoxanes, it is possible to use, for example, the compoundsdescribed in WO 00/31090. Particularly useful aluminoxanes areopen-chain or cyclic aluminoxane compounds of the general formula (X) or(XI)

where R^(1D)-R^(4D) are each, independently of one another, aC₁-C₆-alkyl group, preferably a methyl, ethyl, butyl or isobutyl groupand l is an integer from 1 to 40, preferably from 4 to 25.

A particularly useful aluminoxane compound is methylaluminoxane.

These oligomeric aluminoxane compounds are usually prepared bycontrolled reaction of a solution of a trialkylaluminum, in particulartrimethylaluminum, with water. In general, the oligomeric aluminoxanecompounds obtained are in the form of mixtures of both linear and cyclicchain molecules of various lengths, so that l is to be regarded as amean. The aluminoxane compounds can also be present in admixture withother metal alkyls, usually aluminum alkyls. Aluminoxane preparationssuitable as component (C) are commercially available.

Furthermore modified aluminoxanes in which some of the hydrocarbonradicals have been replaced by hydrogen atoms or alkoxy, aryloxy, siloxyor amide radicals can also be used in place of the aluminoxane compoundsof the formula (X) or (XI) as component (C).

It has been found to be advantageous to use the transition metal complexA) or the iron complex B) and the aluminoxane compounds in such amountsthat the atomic ratio of aluminum from the aluminoxane compoundsincluding any aluminum alkyl still present to the transition metal fromthe transition metal complex (A) is in the range from 1:1 to 2000:1,preferably from 10:1 to 500:1 and in particular in the range from 20:1to 400:1. The atomic ratio of aluminum from the aluminoxane compoundsincluding any aluminum alkyl still present to the iron from the ironcomplex (B) is usually in the range from 1:1 to 2000:1, preferably from10:1 to 500:1 and in particular in the range from 20:1 to 400:1.

A further class of suitable activating components (C) arehydroxyaluminoxanes. These can be prepared, for example, by addition offrom 0.5 to 1.2 equivalents of water, preferably from 0.8 to 1.2equivalents of water, per equivalent of aluminum to an alkylaluminumcompound, in particular triisobutylaluminum, at low temperatures,usually below 0° C. Such compounds and their use in olefinpolymerization are described, for example, in WO 00/24787. The atomicratio of aluminum from the hydroxyaluminoxane compound to the transitionmetal from the transition metal complex (A) or the iron complex (B) isusually in the range from 1:1 to 100:1, preferably from 10:1 to 50:1 andin particular in the range from 20:1 to 40:1. Preference is given tousing a hafnocene dialkyl compound (A).

As strong, uncharged Lewis acids, preference is given to compounds ofthe general formula (XII)M^(2D)X^(1D)X^(2D)X^(3D)  (XII)

where

-   M^(2D) is an element of group 13 of the Periodic Table of the    Elements, in particular B, Al or Ga, preferably B,-   X^(1D), X^(2D) and X^(3D) are each hydrogen, C₁-C₁₀-alkyl,    C₆-C₁₅-aryl, alkylaryl, arylalkyl, haloalkyl or haloaryl each having    from 1 to 10 carbon atoms in the alkyl part and from 6 to 20 carbon    atoms in the aryl part or fluorine, chlorine, bromine or iodine, in    particular haloaryls, preferably pentafluorophenyl.

Further examples of strong, uncharged Lewis acids are given in WO00/31090.

Compounds which are particularly useful as component (C) are boranes andboroxins such as trialkylborane, triarylborane or trimethylboroxin.Particular preference is given to using boranes which bear at least twoperfluorinated aryl radicals. Particular preference is given tocompounds of the general formula (XII) in which X^(1D), X^(2D) andX^(3D) are identical, for example triphenylborane,tris(4-fluorophenyl)borane, tris(3,5-difluorophenyl)borane,tris(4-fluoromethylphenyl)borane, tris(pentafluorophenyl)borane,tris(tolyl)borane, tris(3,5-dimethylphenyl)borane,tris(3,5-difluorophenyl)borane or tris(3,4,5-trifluorophenyl)borane.Preference is given to using tris(penta-fluorophenyl)borane.

Suitable compounds (C) are preferably prepared by reaction of aluminumor boron compounds of the formula (XII) with water, alcohols, phenolderivatives, thiophenol derivatives or aniline derivatives, withhalogenated and especially perfluorinated alcohols and phenols being ofparticular importance. Examples of particularly useful compounds arepentafluorophenol, 1,1-bis(pentafluoro-phenyl)methanol and4-hydroxy-2,2′,3,3′,4′,5,5′,6,6′-nonafluorobiphenyl. Examples ofcombinations of compounds of the formula (XII) with Broenstedt acidsare, in particular, trimethylaluminum/pentafluorophenol,trimethylaluminum/1-bis(pentafluorophenyl)methanol,trimethylaluminum/4-hydroxy-2,2′,3,3′,4′,5,5′,6,6′-nonafluorobiphenyl,triethylaluminum/pentafluorophenol andtriisobutylaluminum/pentafluorophenol andtriethylaluminum/4,4′-dihydroxy-2,2′,3,3′,5,5′,6,6′-octafluorobiphenylhydrate.

In further suitable aluminum and boron compounds of the formula (XII),R^(1D) is an OH group, such as, for example, in boronic acids andborinic acids. Particular mention may be made of borinic acids havingperfluorinated aryl radicals, for example (C₆F₅)₂BOH.

Strong uncharged Lewis acids suitable as activating compounds (C) alsoinclude the reaction products of the reaction of a boronic acid with twoequivalents of an aluminum trialkyl or the reaction products of thereaction of an aluminum trialkyl with two equivalents of an acidicfluorinated, in particular perfluorinated, carbon compound such aspentafluorophenol or bis(pentafluorophenyl)borinic acid.

Suitable ionic compounds having Lewis-acid cations include salt-likecompounds of the cation of the general formula (XIII)[((M^(3D))^(a+))Q₁Q₂ . . . Q_(z)]^(d+)  (XIII)

where

-   M^(3D) is an element of groups 1 to 16 of the Periodic Table of the    Elements,-   Q₁ to Q_(z) are simply negatively charged radicals such as    C₁-C₂₈-alkyl, C₆-C₁₅-aryl, alkyl-aryl, arylalkyl, haloalkyl,    haloaryl each having from 6 to 20 carbon atoms in the aryl part and    from 1 to 28 carbon atoms in the alkyl part, C₃-C₁₀-cycloalkyl which    may bear C₁-C₁₀-alkyl groups as substituents, halogen,    C₁-C₂₈-alkoxy, C₆-C₁₅-aryloxy, silyl or mercaptyl groups,-   a is an integer from 1 to 6 and-   z is an integer from 0 to 5,-   d corresponds to the difference a−z, but d is greater than or equal    to 1.

Particularly useful cations are carbonium cations, oxonium cations andsulfonium cations and also cationic transition metal complexes.Particular mention may be made of the triphenylmethyl cation, the silvercation and the 1,1′-dimethylferrocenyl cation. They preferably havenoncoordinating counterions, in particular boron compounds as are alsomentioned in WO 91/09882, preferably tetrakis(pentafluorophenyl)borate.

Salts having noncoordinating anions can also be prepared by combining aboron or aluminum compound, e.g. an aluminum alkyl, with a secondcompound which can react to link two or more boron or aluminum atoms,e.g. water, and a third compound which forms with the boron or aluminiumcompound an ionizing ionic compound, e.g. triphenylchloromethane, oroptionally a base, preferably an organic nitrogen-containing base, forexample an amine, an aniline derivative or a nitrogen heterocycle. Inaddition, a fourth compound which likewise reacts with the boron oraluminum compound, e.g. pentafluorophenol, can be added.

Ionic compounds containing Brönsted acids as cations preferably likewisehave noncoordinating counterions. As Brönsted acid, particularpreference is given to protonated amine or aniline derivatives.Preferred cations are N,N-dimethylanilinium,N,N-dimethylcyclohexylammonium and N,N-dimethylbenzylammonium and alsoderivatives of the latter two.

Compounds containing anionic boron heterocycles as are described in WO9736937 are also suitable as component (C), in particulardimethylanilinium boratabenzenes or trityl boratabenzenes.

Preferred ionic compounds C) contain borates which bear at least twoperfluorinated aryl radicals. Particular preference is given toN,N-dimethylanilinium tetrakis(pentafluorophenyl)borate and inparticular N,N-dimethylcyclohexylammoniumtetrakis(pentafluorophenyl)borate, N,N-dimethylbenzylammoniumtetrakis(pentafluorophenyl)borate or trityltetrakispentafluorophenylborate.

It is also possible for two or more borate anions to be joined to oneanother, as in the dianion [(C₆F₅)₂B—C₆F₄—B(C₆F₅)₂]²⁻, or the borateanion can be bound via a bridge to a suitable functional group on thesupport surface.

Further suitable activating compounds (C) are listed in WO 00/31090.

The amount of strong, uncharged Lewis acids, ionic compounds havingLewis-acid cations or ionic compounds containing Brönsted acids ascations is preferably from 0.1 to 20 equivalents, more preferably from 1to 10 equivalents and particularly preferably from 1 to 2 equivalents,based on the transition metal complex (A) or the iron complex (B).

Suitable activating compounds (C) also include boron-aluminum compoundssuch as di[bis(penta-fluorophenylboroxy)]methylalane. Examples of suchboron-aluminum compounds are those disclosed in WO 99/06414.

It is also possible to use mixtures of all the abovementioned activatingcompounds (C). Preferred mixtures comprise aluminoxanes, in particularmethylaluminoxane, and an ionic compound, in particular one containingthe tetrakis(pentafluorophenyl)borate anion, and/or a strong unchargedLewis acid, in particular tris(pentafluorophenyl)borane or a boroxin.

Both the transition metal complex (A) or the iron complex (B) and theactivating compounds (C) are preferably used in a solvent, preferably anaromatic hydrocarbon having from 6 to 20 carbon atoms, in particularxylenes, toluene, pentane, hexane, heptane or a mixture thereof.

A further possibility is to use an activating compound (C) which cansimultaneously be employed as support (D). Such systems are obtained,for example, from an inorganic oxide treated with zirconium alkoxide andsubsequent chlorination, e.g. by means of carbon tetrachloride. Thepreparation of such systems is described, for example, in WO 01/41920.

Combinations of the preferred embodiments of (C) with the preferredembodiments of (A) and/or (B) are particularly preferred.

As joint activator (C) for the catalyst component (A) and (B),preference is given to using an aluminoxane. Preference is also given tothe combination of salt-like compounds of the cation of the generalformula (XIII), in particular N,N-dimethylaniliniumtetrakis(pentafluorophenyl)borate, N,N-dimethylcyclohexylammoniumtetrakis(pentafluorophenyl)borate, N,N-dimethylbenzyl-ammoniumtetrakis(pentafluorophenyl)borate or trityltetrakispentafluorophenylborate, as activator (C) for hafnocenes (A), inparticular in combination with an aluminoxane as activator (C) for theiron complex (B).

Further particularly useful joint activators (C) are the reactionproducts of aluminum compounds of the formula (XII) with perfluorinatedalcohols and phenols.

To enable the transition metal complex (A) and the iron complex (B) tobe used in polymerization processes in the gas phase or in suspension,it is often advantageous to use the complexes in the form of a solid,i.e. for them to be applied to a solid support (D). Furthermore, thesupported complexes have a high productivity. The transition metalcomplexes (A) and/or the iron complex (B) can therefore also optionallybe immobilized on an organic or inorganic support (D) and be used insupported form in the polymerization. This enables, for example,deposits in the reactor to be avoided and the polymer morphology to becontrolled. As support materials, preference is given to using silicagel, magnesium chloride, aluminum oxide, mesoporous materials,aluminosilicates, hydrotalcites and organic polymers such aspolyethylene, polypropylene, polystyrene, polytetrafluoroethylene orpolymers bearing polar functional groups, for example copolymers ofethene and acrylic esters, acrolein or vinyl acetate.

Particular preference is given to a catalyst system comprising at leastone transition metal complex (A), at least one iron complex (B), atleast one activating compound (C) and at least one support component(D).

The preferred catalyst composition according to the invention comprisesone or more support components. It is possible for both the transitionmetal component (A) and the iron complex (B) to be supported, or onlyone of the two components can be supported. In a preferred embodiment,both the components (A) and (B) are supported. The two components (A)and (B) can in this case be applied to different supports or together ona joint support. The components (A) and (B) are preferably applied to ajoint support in order to ensure a relatively close spatial proximity ofthe various catalyst centers and thus to ensure good mixing of thedifferent polymers formed.

To prepare the catalyst systems of the invention, preference is given toimmobilizing one of the components (A) and one of the components (B)and/or activator (C) or the support (D) by physisorption or else bymeans of a chemical reaction, i.e. covalent binding of the components,with reactive groups on the support surface.

The order in which support component D), transition metal complex (A),iron complex (B) and the activating compounds (C) are combined is inprinciple immaterial. After the individual process steps, the variousintermediates can be washed with suitable inert solvents such asaliphatic or aromatic hydrocarbons.

Transition metal complex (A), iron complex (B) and the activatingcompound (C) can be immobilized independently of one another, e.g. insuccession or simultaneously. Thus, the support component (D) canfirstly be brought into contact with the activating compound orcompounds (C) or the support component (D) can firstly be brought intocontact with the transition metal complex (A) and/or the iron complex(B). Preactivation of the transition metal complex A) by means of one ormore activating compounds (C) prior to mixing with the support (D) isalso possible. The iron component can, for example, be reactedsimultaneously with the transition metal complex with the activatingcompound (C), or can be preactivated separately by means of the latter.The preactivated iron complex (B) can be applied to the support beforeor after the preactivated transition metal complex (A). In one possibleembodiment, the transition metal complex (A) and/or the iron complex (B)can also be prepared in the presence of the support material. A furthermethod of immobilization is prepolymerization of the catalyst systemwith or without prior application to a support.

The immobilization is generally carried out in an inert solvent whichcan be removed by filtration or evaporation after the immobilization.After the individual process steps, the solid can be washed withsuitably inert solvents such as aliphatic or aromatic hydrocarbons anddried. However, the use of the still moist, supported catalyst is alsopossible.

In a preferred method of preparing the supported catalyst system, atleast one iron complex (B) is brought into contact with an activatedcompound (C) and subsequently mixed with the dehydrated or passivatedsupport material (D). The transition metal complex (A) is likewisebrought into contact with at least one activating compound (C) in asuitable solvent, preferably giving a soluble reaction product, anadduct or a mixture. The preparation obtained in this way is then mixedwith the immobilized iron complex, which is used directly or after thesolvent has been separated off, and the solvent is completely or partlyremoved. The resulting supported catalyst system is preferably dried toensure that all or most of the solvent is removed from the pores of thesupport material. The supported catalyst is preferably obtained as afree-flowing powder. Examples of the industrial implementation of theabove process are described in WO 96/00243, WO 98/40419 or WO 00/05277.A further preferred embodiment comprises firstly producing theactivating compound (C) on the support component (D) and subsequentlybringing this supported compound into contact with the transition metalcomplex (A) and the iron complex (B).

As support component (D), preference is given to using finely dividedsupports which can be any organic or inorganic solid. In particular, thesupport component (D) can be a porous support such as talc, a sheetsilicate such as montmorillonite, mica or an inorganic oxide or a finelydivided polymer powder (e.g. polyolefin or a polymer having polarfunctional groups).

The support materials used preferably have a specific surface area inthe range from 10 to 1000 m²/g, a pore volume in the range from 0.1 to 5ml/g and a mean particle size of from 1 to 500 μm. Preference is givento supports having a specific surface area in the range from 50 to 700m²/g, a pore volume in the range from 0.4 to 3.5 ml/g and a meanparticle size in the range from 5 to 350 μm. Particular preference isgiven to supports having a specific surface area in the range from 200to 550 m²/g, a pore volume in the range from 0.5 to 3.0 ml/g and a meanparticle size of from 10 to 150 μm.

The transition metal complex (A) is preferably applied in such an amountthat the concentration of the transition metal from the transition metalcomplex (A) in the finished catalyst system is from 1 to 200 μmol,preferably from 5 to 100 μmol and particularly preferably from 10 to 70μmol, per g of support (D). The iron complex (B) is preferably appliedin such an amount that the concentration of iron from the iron complex(B) in the finished catalyst system is from 1 to 200 μmol, preferablyfrom 5 to 100 μmol and particularly preferably from 10 to 70 μmol, per gof support (D).

The inorganic support can be subjected to a thermal treatment, e.g. toremove adsorbed water. Such a drying treatment is generally carried outat temperatures in the range from 50 to 1000° C., preferably from 100 to600° C., with drying at from 100 to 200° C. preferably being carried outunder reduced pressure and/or under a blanket of inert gas (e.g.nitrogen), or the inorganic support can be calcined at temperatures offrom 200 to 1000° C. to produce the desired structure of the solidand/or set the desired OH concentration on the surface. The support canalso be treated chemically using customary dessicants such as metalalkyls preferably aluminum alkyls, chlorosilanes or SiCl₄, or elsemethylaluminoxane. Appropriate treatment methods are described, forexample, in WO 00/31090.

The inorganic support material can also be chemically modified. Forexample, treatment of silica gel with NH₄SiF₆ or other fluorinatingagents leads to fluorination of the silica gel surface, or treatment ofsilica gels with silanes containing nitrogen-, fluorine- orsulfur-containing groups leads to correspondingly modified silica gelsurfaces.

Organic support materials such as finely divided polyolefin powders(e.g. polyethylene, poly-propylene or polystyrene) can also be used andare preferably likewise freed of adhering moisture, solvent residues orother impurities by appropriate purification and drying operationsbefore use. It is also possible to use functionalized polymer supports,e.g. ones based on polystyrene, polyethylene, polypropylene orpolybutylene, via whose functional groups, for example ammonium orhydroxy groups, at least one of the catalyst components can beimmobilized. It is also possible to use polymer blends.

Inorganic oxides suitable as support component (D) may be found amongthe oxides of elements of groups 2, 3, 4, 5, 13, 14, 15 and 16 of thePeriodic Table of the Elements. Examples of oxides preferred as supportsinclude silicon dioxide, aluminum oxide and mixed oxides of the elementscalcium, aluminum, silicon, magnesium or titanium and also correspondingoxide mixtures. Other inorganic oxides which can be used alone or incombination with the abovementioned preferred oxidic supports are, forexample, MgO, CaO, AlPO₄, ZrO₂, TiO₂, B₂O₃ or mixtures thereof.

Further preferred inorganic support materials are inorganic halides suchas MgCl₂ or carbonates such as Na₂CO₃, K₂CO₃, CaCO₃, MgCO₃, sulfatessuch as Na₂SO₄, Al₂(SO₄)₃, BaSO₄, nitrates such as KNO₃, Mg(NO₃)₂ orAl(NO₃)₃.

As solid support materials (D) for catalysts for olefin polymerization,preference is given to using silica gels since particles whose size andstructure make them suitable as supports for olefin polymerization canbe produced from this material. Spray-dried silica gels, which arespherical agglomerates of relatively small granular particles, i.e.primary particles, have been found to be particularly useful. The silicagels can be dried and/or calcined before use.

Further preferred supports (D) are hydrotalcites and calcinedhydrotalcites. In mineralogy, hydrotalcite is a natural mineral havingthe ideal formulaMg₆Al₂(OH)₁₆CO₃.4H₂Owhose structure is derived from that of brucite Mg(OH)₂. Brucitecrystallizes in a sheet structure with the metal ions in octahederalholes between two layers of close-packed hydroxyl ions, with only everysecond layer of the octahederal holes being occupied. In hydrotalcite,some magnesium ions are replaced by aluminum ions, as a result of whichthe packet of layers gains a positive charge. This is balanced by theanions which are located together with water of crystallization in thelayers in-between.

Such sheet structures are found not only inmagnesium-aluminum-hydroxides, but generally in mixed metal hydroxidesof the general formulaM(II)_(2x) ²⁺M(III)₂ ³⁺(OH)_(4x+4).A_(2/n) ^(n−) .zH₂Owhich have a sheet structure and in which M(II) is a divalent metal suchas Mg, Zn, Cu, Ni, Co, Mn, Ca and/or Fe and M(III) is a trivalent metalsuch as Al, Fe, Co, Mn, La, Ce and/or Cr, x is a number from 0.5 to 10in steps of 0.5, A is an interstitial anion and n is the charge on theinterstitial anion which can be from 1 to 8, usually from 1 to 4, and zis an integer from 1 to 6, in particular from 2 to 4. Possibleinterstitial anions are organic anions such as alkoxide anions, alkylether sulfates, aryl ether sulfates or glycol ether sulfates, inorganicanions such as, in particular, carbonate, hydrogen carbonate, nitrate,chloride, sulfate or B(OH)₄ ⁻ or polyoxometal anions such as Mo₇O₂₄ ⁶⁻or V₁₀O₂₈ ⁶⁻. However, a mixture of a plurality of such anions is alsopossible.

Accordingly, all such mixed metal hydroxides having a sheet structureshould be regarded as hydrotalcites for the purposes of the presentinvention.

Calcined hydrotalcites can be prepared from hydrotalcites bycalcination, i.e. heating, by means of which, inter alia, the desiredhydroxide group content can be set. In addition, the crystal structurealso changes. The preparation of the calcined hydrotalcites usedaccording to the invention is usually carried out at temperatures above180° C. Preference is given to calcination for a period of from 3 to 24hours at temperatures of from 250° C. to 1000° C., in particular from400° C. to 700° C. It is possible for air or inert gas to be passed overthe solid or for a vacuum to be applied at the same time.

On heating, the natural or synthetic hydrotalcites firstly give offwater, i.e. drying occurs. On further heating, the actual calcination,the metal hydroxides are converted into the metal oxides by eliminationof hydroxyl groups and interstitial anions; OH groups or interstitialanions such as carbonate can also still be present in the calcinedhydrotalcites. A measure of this is the loss on ignition. This is theweight loss experienced by a sample which is heated in two steps firstlyfor 30 minutes at 200° C. in a drying oven and then for 1 hour at 950°C. in a muffle furnace.

The calcined hydrotalcites used as component (D) are thus mixed oxidesof the divalent and trivalent metals M(II) and M(III), with the molarratio of M(II) to M(III) generally being in the range from 0.5 to 10,preferably from 0.75 to 8 and in particular from 1 to 4. Furthermore,normal amounts of impurities, for example Si, Fe, Na, Ca or Ti and alsochlorides and sulfates, can also be present.

Preferred calcined hydrotalcites (D) are mixed oxides in which M(II) ismagnesium and M(III) is aluminum. Such aluminum-magnesium mixed oxidesare obtainable from Condea Chemie GmbH (now Sasol Chemie), Hamburg underthe trade name Puralox Mg.

Preference is also given to calcined hydrotalcites in which thestructural transformation is complete or virtually complete.Calcination, i.e. transformation of the structure, can be confirmed, forexample, by means of X-ray diffraction patterns.

The hydrotalcites, calcined hydrotalcites or silica gels used aregenerally used as finely divided powders having a mean particle diameterD50 of from 5 to 200 preferably from 10 to 150 μm, particularlypreferably from 15 to 100 μm and in particular from 20 to 70 and usuallyhave pore volumes of from 0.1 to 10 cm³/g, preferably from 0.2 to 5cm³/g, and specific surface areas of from 30 to 1000 m²/g, preferablyfrom 50 to 800 m²/g and in particular from 100 to 600 m²/g. Thetransition metal complex (A) is preferably applied in such an amountthat the concentration of the transition metal from the transition metalcomplex (A) in the finished catalyst system is from 1 to 100 μmol,preferably from 5 to 80 μmol and particularly preferably from 10 to 60μmol, per g of support (D).

The catalyst system may further comprise, as additional component (E), ametal compound of the general formula (XX),M^(G)(R^(1G))_(r) _(G) (R^(2G))_(s) _(G) (R^(3G))_(r) _(G)   (XX)

where

-   M^(G) is Li, Na, K, Be, Mg, Ca, Sr, Ba, boron, aluminum, gallium,    indium, thallium, zinc, in particular Li, Na, K, Mg, boron, aluminum    or Zn,-   R^(1G) is hydrogen, C₁-C₁₀-alkyl, C₆-C₁₅-aryl, alkylaryl or    arylalkyl each having from 1 to 10 carbon atoms in the alkyl part    and from 6 to 20 carbon atoms in the aryl part,-   R^(2G) and R^(3G) are each hydrogen, halogen, C₁-C₁₀-alkyl,    C₆-C₁₅-aryl, alkylaryl, arylalkyl or alkoxy each having from 1 to 20    carbon atoms in the alkyl part and from 6 to 20 carbon atoms in the    aryl part, or alkoxy together with C₁-C₁₀-alkyl or C₆-C₁₅-aryl,-   r^(G) is an integer from 1 to 3-   and-   s^(G) and t^(G) are integers from 0 to 2, with the sum    r^(G)+s^(G)+t^(G) corresponding to the valence of M^(G),

where the component (E) is usually not identical to the component (C).It is also possible to use mixtures of various metal compounds of theformula (XX).

Among the metal compounds of the general formula (XX), preference isgiven to those in which M^(G) is lithium, magnesium, boron or aluminumand

-   R^(1G) is C₁-C₂₀-alkyl.

Particularly preferred metal compounds of the formula (XX) aremethyllithium, ethyllithium, n-butyllithium, methylmagnesium chloride,methylmagnesium bromide, ethylmagnesium chloride, ethylmagnesiumbromide, butylmagnesium chloride, dimethylmagnesium, diethylmagnesium,dibutylmagnesium, n-butyl-n-octylmagnesium, n-butyl-n-heptylmagnesium,in particular n-butyl-n-octylmagnesium, tri-n-hexylaluminum,triisobutylaluminum, tri-n-butylaluminum, triethylaluminum,dimethylaluminum chloride, dimethylaluminum fluoride, methylaluminumdichloride, methylaluminum sesquichloride, diethylaluminum chloride andtrimethylaluminum and mixtures thereof. The partial hydrolysis productsof aluminum alkyls with alcohols can also be used.

When a metal compound (E) is used, it is preferably present in thecatalyst system in such an amount that the molar ratio of M^(G) fromformula (XX) to the sum of the transition metals from the transitionmetal complex (A) and the iron complex (B) is from 3000:1 to 0.1:1,preferably from 800:1 to 0.2:1 and particularly preferably from 100:1 to1:1.

In general, the metal compound (E) of the general formula (XX) is usedas constituent of a catalyst system for the polymerization orcopolymerization of olefins. Here, the metal compound (E) can, forexample, be used for preparing a catalyst solid comprising the support(D) and/or be added during or shortly before the polymerization. Themetal compounds (E) used can be identical or different. It is alsopossible, particularly when the catalyst solid contains no activatingcomponent (C), for the catalyst system to further comprise, in additionto the catalyst solid, one or more activating compounds (C) which areidentical to or different from any compounds (E) present in the catalystsolid.

The component E) can likewise be reacted in any order with thecomponents (A), (B) and optionally (C) and (D). The component (A) can,for example, be brought into contact with the component(s) (C) and/or(D) either before or after being brought into contact with the olefinsto be polymerized. Preactivation by means of one or more components (C)prior to mixing with the olefin and further addition of the same oranother component (C) and/or (D) after this mixture has been broughtinto contact with the olefin is also possible. Preactivation isgenerally carried out at temperatures of 10-100° C., preferably 20-80°C.

In another preferred embodiment, a catalyst solid is prepared from thecomponents (A), (B), (C) and (D) as described above and this is broughtinto contact with the component (E) during, at the commencement of orshortly before the polymerization.

Preference is given to firstly bringing (E) into contact with theα-olefin to be polymerized and subsequently adding the catalyst solidcomprising the components (A), (B), (C) and (D) as described above.

In a further, preferred embodiment, the support (D) is firstly broughtinto contact with the component (E), and the components (A) and (B) andany further activator (C) are then dealt with as described above.

It is also possible for the catalyst system firstly to be prepolymerizedwith α-olefins, preferably linear C₂-C₁₀-1-alkenes and in particularethylene or propylene, and the resulting prepolymerized catalyst solidthen to be used in the actual polymerization. The mass ratio of catalystsolid used in the prepolymerization to a monomer polymerized onto it isusually in the range from 1:0.1 to 1:1000, preferably from 1:1 to 1:200.

Furthermore, a small amount of an olefin, preferably an α-olefin, forexample vinylcyclohexane, styrene or phenyldimethylvinylsilane, asmodifying component, an antistatic or a suitable inert compound such asa wax or oil can be added as additive during or after the preparation ofthe catalyst system. The molar ratio of additives to the sum oftransition metal compound (A) and iron complex (B) is usually from1:1000 to 1000:1, preferably from 1:5 to 20:1.

The catalyst composition or catalyst system of the invention is suitablefor preparing the polyethylene of the invention, which has advantageoususe and processing properties.

To prepare the polyethylene of the invention, the ethylene ispolymerized as described above with 1-alkenes having from 3 to 10 carbonatoms.

In the copolymerization process of the invention, ethylene ispolymerized with 1-alkenes having from 3 to 12 carbon atoms. Preferred1-alkenes are linear or branched C₂-C₁₀-1-alkenes, in particular linearC₂-C₈₁-alkenes such as ethene, propene, 1-butene, 1-pentene, 1-hexene,1-heptene, 1-octene or branched C₂-C₁₀-1-alkenes such as4-methyl-1-pentene. Particularly preferred 1-alkenes areC₄-C₁₀-1-alkenes, in particular linear C₆-C₁₀-1-alkenes. It is alsopossible to polymerize mixtures of various 1-alkenes. Preference isgiven to polymerizing at least one 1-alkene selected from the groupconsisting of ethene, propene, 1-butene, 1-pentene, 1-hexene, 1-heptene,1-octene and 1-decene. Monomer mixtures containing at least 50 mol % ofethene are preferably used.

The process of the invention for polymerizing ethylene with 1-alkenescan be carried out using all industrially known polymerization methodsat temperatures in the range from −60 to 350° C., preferably from 0 to200° C. and particularly preferably from 25 to 150° C., and underpressures of from 0.5 to 4000 bar, preferably from 1 to 100 bar andparticularly preferably from 3 to 40 bar. The polymerization can becarried out in a known manner in bulk, in suspension, in the gas phaseor in a supercritical medium in the customary reactors used for thepolymerization of olefins. It can be carried out batchwise or preferablycontinuously in one or more stages. High-pressure polymerizationprocesses in tube reactors or autoclaves, solution processes, suspensionprocesses, stirred gas-phase processes and gas-phase fluidized-bedprocesses are all possible.

The polymerizations are usually carried out at temperatures in the rangefrom −60 to 350° C., preferably in the range from 20 to 300° C., andunder pressures of from 0.5 to 4000 bar. The mean residence times areusually from 0.5 to 5 hours, preferably from 0.5 to 3 hours. Theadvantageous pressure and temperature ranges for carrying out thepolymerizations usually depend on the polymerization method. In the caseof high-pressure polymerization processes, which are customarily carriedout at pressures of from 1000 to 4000 bar, in particular from 2000 to3500 bar, high polymerization temperatures are generally also set.Advantageous temperature ranges for these high-pressure polymerizationprocesses are from 200 to 320° C., in particular from 220 to 290° C. Inthe case of low-pressure polymerization processes, it is usual to set atemperature which is at least a few degrees below the softeningtemperature of the polymer. In particular, temperatures of from 50 to180° C., preferably from 70 to 120° C., are set in these polymerizationprocesses. In the case of suspension polymerizations, the polymerizationis usually carried out in a suspension medium, preferably an inerthydrocarbon such as isobutane or mixtures of hydro-carbons or else inthe monomers themselves. The polymerization temperatures are generallyin the range from −20 to 115° C., and the pressure is generally in therange from 1 to 100 bar. The solids content of the suspension isgenerally in the range from 10 to 80%. The polymerization can be carriedout either batchwise, e.g. in stirring autoclaves, or continuously, e.g.in tube reactors, preferably in loop reactors. Particular preference isgiven to employing the Phillips PF process as described in U.S. Pat. No.3,242,150 and U.S. Pat. No. 3,248,179. The gas-phase polymerization isgenerally carried out in the range from 30 to 125° C. at pressures offrom 1 to 50 bar.

Among the abovementioned polymerization processes, particular preferenceis given to gas-phase polymerization, in particular in gas-phasefluidized-bed reactors, solution polymerization and suspensionpolymerization, in particular in loop reactors and stirred tankreactors. The gas-phase polymerization can also be carried out in thecondensed or supercondensed mode, in which part of the circulating gasis cooled to below the dew point and is recirculated as a two-phasemixture to the reactor. Furthermore, it is possible to use a multizonereactor in which the two polymerization zones are linked to one anotherand the polymer is passed alternately through these two zones a numberof times. The two zones can also have different polymerizationconditions. Such a reactor is described, for example, in WO 97/04015.The different or identical polymerization processes can also, ifdesired, be connected in series so as to form a polymerization cascade,for example as in the Hostalen® process. A parallel reactor arrangementusing two or more identical or different processes is also possible.Furthermore, molar mass regulators, for example hydrogen, or customaryadditives such as antistatics can also be used in the polymerizations.Hydrogen can especially be used to enhance the activity of the hafnocene(A). The hydrogen and increased temperature usually lead to lowerz-average molar mass.

The polymerization is preferably carried out in a single reactor, inparticular in a gas-phase reactor. The polymerization of ethylene with1-alkenes having from 3 to 10 carbon atoms gives the polyethylene of theinvention when the catalyst of the invention is used. The polyethylenepowder obtained directly from the reactor displays a very highhomogeneity, so that, unlike the case of cascade processes, subsequentextrusion is not necessary in order to obtain a homogeneous product.

The production of polymer blends by intimate mixing of individualcomponents, for example by melt extrusion in an extruder or kneader(cf., for example, “Polymer Blends” in Ullmann's Encyclopedia ofIndustrial Chemistry, 6^(th) Edition, 1998, Electronic Release), isoften accompanied by particular difficulties. The melt viscosities ofthe high and low molecular weight components of a bimodal polyethyleneblend are extremely different. While the low molecular weight componentis quite fluid at the customary temperatures of about 190-210° C. usedfor producing the blends, the high molecular weight component is onlysoftened (“lentil soup”). Homogeneous mixing of the two components istherefore for very difficult. In addition, it is known that the highmolecular weight component can easily be damaged as a result of thermalstress and by shear forces in the extruder, so that the properties ofthe blend are adversely affected. The mixing quality of suchpolyethylene blends is therefore often unsatisfactory.

The mixing quality of the polyethylene powder obtained directly from thereactor can be tested by assessing thin slices (“microtome sections”) ofa sample under an optical microscope. Inhomogenities show up in the formof specks or “white spots”. The specs or “white spots” are predominantlyhigh molecular weight, high-viscosity particles in a low-viscositymatrix (cf., for example, U. Burkhardt et al. in “Aufbereiten vonPolymeren mit neuartigen Eigenschaften”, VDI-Verlag, Düsseldorf 1995, p.71). Such inclusions can reach a size of up to 300 μm, cause stresscracks and result in brittle failure of components. The better themixing quality of a polymer, the fewer and smaller are these inclusionsobserved. The mixing quality of a polymer is determined quantitativelyin accordance with ISO 13949. According to the measurement method, amicrotome section is prepared from a sample of the polymer, the numberand size of these inclusions are counted and a grade is determined forthe mixing quality of the polymer according to a set assessment scheme.The mixing quality of the polyethylene of the invention, obtaineddirectly from the reactor is preferably below 3.

The preparation of the polyethylene of the invention in the reactorreduces the energy consumption, requires no subsequent blendingprocesses and makes simple control of the molecular weight distributionsand the molecular weight fractions of the various polymers possible. Inaddition, good mixing of the polyethylene is achieved.

The following examples illustrate the invention without restricting thescope of the invention.

The measured values described were determined in the following way:

NMR samples were placed in tubes under inert gas and, if appropriate,melted. The solvent signals served as internal standard in the ¹H- and¹³C-NMR spectra and their chemical shift was converted into the valuesrelative to TMS.

The vinyl group content is determined by means of IR in accordance withASTM D 6248-98. The branches/1000 carbon atoms are determined by meansof ¹³C-NMR, as described by James. C. Randall, JMS-REV. Macromol. Chem.Phys., C29 (2&3), 201-317 (1989), and are based on the total content ofCH₃ groups/1000 carbon atoms. The side chains larger than CH₃ andespecially ethyl, butyl and hexyl side chain branches/1000 carbon atomsare likewise determined in this way.

The degree of branching in the individual polymer fractions isdetermined by the method of Holtrup (W. Holtrup, Makromol. Chem. 178,2335 (1977)) coupled with ¹³C-NMR.

The density [g/cm³] was determined in accordance with ISO 1183.

The determination of the molar mass distributions and the means Mn, Mw,M_(z) and Mw/Mn derived therefrom was carried out by means ofhigh-temperature gel permeation chromatography on a WATERS 150 C using amethod based on DIN 55672 and the following columns connected in series:3× SHODEX AT 806 MS, 1× SHODEX UT 807 and 1× SHODEX AT-G under thefollowing conditions: solvent: 1,2,4-trichlorobenzene (stabilized with0.025% by weight of 2,6-di-tert-butyl-4-methylphenol), flow: 1 ml/min,500 μl injection volume, temperature: 140° C. The columns werecalibrated with polyethylene standards with molar masses of from 100 bis10⁷ g/mol. The evaluation was carried out by using the Win-GPC softwareof Fa. HS-Entwicklungsgesellschaft für wissenschaftliche Hard- andSoftware mbH, Ober-Hilbersheim.

For the purposes of the present invention, the expression “HLMI” refers,as is generally known, to the “high load melt flow rate” and is alwaysdetermined at 190° C. under a load of 21.6 kg (190° C./21.6 kg) inaccordance with ISO 1133.

The haze was determined by ASTM D 1003-00 on a BYK Gardener Haze GuardPlus Device on at least 5 pieces of film 10×10 cm with a thickness of 50μm. The dart drop was determined by ASTM D 1709 Method A on a film witha thickness of 50 μm. The clarity was determined by ASTM D 1746-03 on aBYK Gardener Haze Guard Plus Device, calibrated with calibration cell77.5, on at least 5 pieces of film 10×10 cm with a thickness of 50 μm.The gloss 45° was determined by ASTM D 2457-03 on a gloss meter 45° witha vacuum plate for fixing the film, on at least 5 pieces of film with athickness of 50 μm.

Abbreviations in the table below:

Cat. Catalyst T(poly) Polymerisation temperature M_(w) Weight averagemolar mass M_(n) Number average molar mass M_(z) z-average molar massDensity Polymer density Prod. Productivity of the catalyst in g ofpolymer obtained per g of catalyst used per hour total-CH3 is the amountof CH3-groups per 1000C including end groups —HC═CH2 is the amount ofvinyl groups >C═CH2 is the amount of vinylidene groups

GPC % at molar mass 1 million g/mol. is the % by weight according to gelpermeation chromatography below a molar mass of 1 million g/mol.

Bis(n-butylcyclopentadienyl)hafnium dichloride is commercially availablefrom Crompton.

Preparation of the Individual Components

2,6-Bis[1-(2-tert.butylphenylimino)ethyl]pyridine was prepared as inexample 6 of WO 98/27124 and2,6-Bis[1-(2-tert.butylphenylimino)ethyl]pyridine iron(II) dichloridewas prepared as in example 15 of WO 98/27124.

2,6-Bis[1-(2,4,6-trimethylphenylimino)ethyl]pyridine was prepared as inexample 1 of WO 98/27124 and reacted in an analogous manner withiron(II) chloride to give2,6-Bis[1-(2,4,6-trimethylphenylimino)ethyl]pyridine iron(II)dichloride, as likewise disclosed in WO 98/27124.

2,6-Bis[1-(2,4-dichloro-6-methylphenylimino)ethyl]pyridine iron(II)dichloride was prepared according to the method of Qian et al.,Organometallics 2003, 22, 4312-4321. Here, 65.6 g of2,6-diacetylpyridine (0.4 mol), 170 g of 2,4-dichloro-6-methylaniline(0.483 mol), 32 g of silica gel type 135 and 160 g of molecular sieves(4 Å) were stirred in 1500 ml of toluene at 80° C. for 5 hours and afurther 32 g of silica gel type 135 and 160 g of molecular sieves (4 Å)were subsequently added. The mixture was stirred at 80° C. for a further8 hours, the insoluble solid was filtered off and washed twice withtoluene. The solvent was distilled off from the filtrate obtained inthis way, the residue was admixed with 200 ml of methanol andsubsequently stirred at 55° C. for 1 hour. The suspension formed in thisway was filtered and the solid obtained was washed with methanol andfreed of the solvent. This gave 95 g of2,6-Bis[1-(2,4,6-trimethylphenylimino)ethyl]pyridine in 47% yield. Thereaction with iron(II) chloride was carried out as described by Qian etal., Organometallics 2003, 22, 4312-4321.

Preparation of the Mixed Catalyst Systems EXAMPLE 1

a) Support Pretreatment

XPO-2107, a spray-dried silica gel from Grace, was baked at 600° C. for6 hours and subsequently 252.2 g of the dried silica gel admixed with164.5 ml of MAO (4.75 M in Toluol, 0.78 mol). The mixture was stirredfor one hour, filtered, the solid washed with toluene and then diedunder reduced pressure.

b) Preparation of the Mixed Catalyst Systems

A mixture of 1.48 g (2.45 mmol) of2,6-Bis[1-(2,4-dichloro-6-methylphenylimino)ethyl]pyridine iron(II)dichloride, 3.61 g (7.34 mmol) of bis(n-butylcyclopentadienyl)hafniumdichloride and 159.6 ml of MAO (4.75 M in toluene, 0.76 mol) was stirredat room temperature for 1 h and subsequently added while stirring to asuspension of 237.1 g of the pretreated support material a) in 800 ml oftoluene. The mixture was stirred at room temperature for a further 3hours, the resulting solid filtered off and washed with toluene. Thesolid was dried under reduced pressure until it was free-flowing. Thisgave 256.7 g of catalyst.

EXAMPLE 2

a) Support Pretreatment

XPO-2107, a spray-dried silica gel from Grace, was baked at 600° C. for6 hours.

b) Preparation of the Mixed Catalyst Systems

A mixture of 5.35 g (9.69 mmol) of2,6-Bis[1-(2-tert.butylphenylimino)ethyl]pyridine iron(II) dichloride,7.49 g (15.22 mmol) of bis(n-butylcyclopentadienyl)hafnium dichlorideand 472 ml of MAO (4.75 M in toluene, 2.24 mol) was stirred at roomtemperature for 30 minutes and subsequently added while stirring to asuspension of 276.8 g of the pretreated support material a) during thecourse of 45 minutes ((Fe+Hf):Al=1:90). The solid was dried underreduced pressure until it was free-flowing. This gave 609 g of catalystwhich still contained 31.5% by weight of solvent (based on the totalweight and calculated on the basis of complete application of allcomponents to the support).

EXAMPLE 3

a) Support Pretreatment

XPO-2107, a spray-dried silica gel from Grace, was baked at 600° C. for6 hours.

b) Preparation of the Mixed Catalyst Systems

A mixture of 1.6 g (2.89 mmol) of2,6-Bis[1-(2-tert.butylphenylimino)ethyl]pyridine iron(II) dichloride,2.05 g (3.71 mmol) of bis(n-butylcyclopentadienyl)hafnium dichloride and194.5 ml of MAO (4.75 M in toluene, 0.924 mmol) was stirred at roomtemperature for 15 minutes and subsequently added while stirring to asuspension of 95.5 g of the pretreated support material a)((Fe+Hf):Al=1:140) in 430 ml toluene. After 2 hours the suspension wasfiltrated and washed with 500 ml of toluene. The residual solid wasdried under reduced pressure until it was free-flowing powder. Thecatalyst still contained 25.2% by weight of solvent (based on the totalweight and calculated on the basis of complete application of allcomponents to the support).

COMPARATIVE EXAMPLE C1

a) Support Pretreatment

XPO-2107, a spray-dried silica gel from Grace, was baked at 600° C. for6 hours.

b) Preparation of the Mixed Catalyst Systems

A mixture of 0.99 g (1.755 mmol) of2,6-Bis[1-(2,4,6-trimethylphenylimino)ethyl]pyridine iron(II)dichloride, 3.69 g (7.5 mmol) of bis(n-butylcyclopentadienyl)hafniumdichloride and 203.8 ml of MAO (4.75 M in toluene, 0.968 mol) wasstirred at room temperature for one hour and subsequently added whilestirring to a suspension of 125 g of the pretreated support material a)((Fe+Hf):Al=1:105). The mixture was stirred for another 2 h, the solventremoved under reduced pressure and then the solid dried under reducedpressure until it was free-flowing. The resulting catalyst stillcontained 38.9% by weight of solvent (based on the total weight andcalculated on the basis of complete application of all components to thesupport).

COMPARATIVE EXAMPLE C2

a) Support Pretreatment

XPO-2107, a spray-dried silica gel from Grace, was baked at 600° C. for6 hours.

b) Preparation of the Mixed Catalyst Systems

A mixture of 5.6 g (11.39 mmol) of bis(n-butylcyclopentadienyl)hafniumdichloride and 297 ml of MAO (4.75 M in toluene, 1.41 mol) was stirredat room temperature for one hour and subsequently added while stirringto 228 g of the pretreated support material a) (Hf:Al=1:120). Themixture was stirred for another 20 minutes and dried under reducedpressure until it was free-flowing. The resulting catalyst stillcontained 33.3% by weight of solvent (based on the total weight andcalculated on the basis of complete application of all components to thesupport). This gave 460 g free flowing catalyst.

Polymerization of the Catalysts

The polymerization was carried out in a fluidized-bed reactor having adiameter of 0.5 m. The reaction temperature, output and the compositionof the reactor gas are reported in Table 1, and the pressure in thereactor was 20 bar. 0.1 g of triisobutylaluminum per hour were meteredin in each case. Catalysts employed were the catalysts from theexamples. The properties of the polymers obtained are summarized inTable 2.

TABLE 1 Polymerization results Catalyst T(poly) Output Ethylene 1-HexeneH₂ from Ex. [° C.] [kg/h] [kg/h] [g/h] [l/h] 1 105 3.2 4 52 1.47 2 943.8 5 100 0.57 3 100 3.1 3.4 85 0.67 C1 94 4.4 5.2 147 4.15 C2 100 4.85.4 136 4.09

TABLE 2 Catalyst from Example 1 2 3 C1 C2 Density [g/cm³] 0.9434 0.94390.938 0.9413 0.935 Etavis/EtaGPC 0.895 0.885 0.895 0.988 n.d. Mw [g/mol]141769 126115 161781 240628 151049 Mw/Mn 8.12 13.23 12.44 9.07 3.7 Mz396696 380177 485941 1339939 279249 GPC % at molar mass 1Mio 99.39299.529 98.948 95.406 99.896 —HC═CH2 [1/1000C] 0.75 1.91 1.2 0.340.07 >C═CH2 [1/1000C] 0.15 0.2 0.2 0.17 0.09 total-CH3 [1/1000C] 4.3 6.56.4 5 4.9 Butyl side chains [1/1000C] 2.67 3.83 4.67 4.17 2.7 HLMI [g/10min.] 22 43 16 11 25

Granulation and Film Extrusion

The obtained polyethylenes were homogenised and granulated on a ZSK 30(Werner Pfleiderer) with screw combination 8A. The processingtemperature was 220° C., the screw speed 250/min with maximum output at20 kg/h. 1500 ppm Irganox B215 were added to stabilize thepolyethylenes.

The polymer was extruded into films by blown film extrusion on a Weberfilm extruder equipped with a collapsing device with wooden flattedboards.

The diameter of the ring die was 50 mm, the gap width was 2/50 and theangel in which the cooling air is blown onto the extruded film is 45°.No filters were used. The 25D Extruder with a screw diameter of 30 mmand a screw speed of 50 turns per min which is equivalent to an outputof 5.1 kg/h. The blow-up ratio was 1:2 and eine the haul-off speed 4.9m/10 min. The height of the frost line was 160 mm. Films with athickness of 50 μm were obtained. The processing properties and opticaland mechanical properties of the films are summarized in Table 3.

TABLE 3 Processing properties and optical and mechanical properties ofthe films Film from cat. of Ex. 1 2 3 C1 C2 melt temp. [° C.] 240 225230 241 228 haze [%] 13.9 19.9 10 75.2 22.7 clarity [%] 98.8 97.1 9913.9 94.6 gloss 45° 60.4 49.6 n.d. 7 45 DDI [g] 124 162 330 <60 n.d.

1. A polyethylene which comprises a mixture of ethylene homopolymers andcopolymers of ethylene with 1-alkenes, the polyethylene having an HLMIof 7 to 60 g/10 min, a molar mass distribution width M_(w)/M_(n) of from7 to 15, a density of from 0.93 to 0.95 g/cm³, a weight average molarmass M_(w) of from 50,000 g/mol to 500,000 g/mol and has 2 to 6 branchesof side chains larger than CH₃/1000 carbon atoms, a z-average molecularweight M_(z) of less than 1 million g/mol, wherein 5-50% by weight ofthe polyethylene having the lowest molar masses has a degree ofbranching of less than 12 branches/1000 carbon atoms and 5-50% by weightof the polyethylene having the highest molar masses has a degree ofbranching of more than 1 branch/1000 carbon atoms.
 2. The polyethyleneaccording to claim 1 comprising a bimodal molar mass distribution. 3.The polyethylene according to claim 1, wherein an amount of thepolyethylene with a molar mass of below 1 million g/mol, as determinedby GPC, is above 95.5% by weight.
 4. The polyethylene according to claim1 which has been prepared in a single reactor.
 5. The polyethyleneaccording to claim 1, comprising an Eta(vis)/Eta(GPC) value of thepolyethylene of less than 0.95, wherein Eta(vis) is the intrinsicviscosity as determined according to ISO 1628-1 and -3 and Eta(GPC) isthe viscosity as determined by GPC (gel permeation chromatography)according to DIN 55672, with 1,2,4-Trichlorobenzene, at 140° C.
 6. Afilm comprising a mixture of ethylene homopolymers and copolymers ofethylene with 1-alkenes, the mixture having an HLMI of 7 to 60 g/10 min,a molar mass distribution width M_(w)/M_(n) of from 7 to 15, a densityof from 0.93 to 0.95 g/cm³, a weight average molar mass M_(w) of from50,000 g/mol to 500,000 g/mol and has from 2 to 6 branches of sidechains larger than CH₃/1000 carbon atoms, a z-average molecular weightM_(z) of less than 1 million g/mol, wherein 5-50% by weight of thepolyethylene having the lowest molar masses has a degree of branching ofless than 12 branches/1000 carbon atoms and 5-50% by weight of thepolyethylene having the highest molar masses has a degree of branchingof more than 1 branch/1000 carbon atoms.
 7. The film according to claim6 selected from stretch films, hygienic films, films for office uses,sealing layers, automatic packaging films, composite or laminatingfilms.
 8. Carrier bags comprising a film, the film comprising a mixtureof ethylene homopolymers and copolymers of ethylene with 1-alkenes, themixture having an HLMI of 7 to 60 g/10 min, a molar mass distributionwidth M_(w)/M_(n) of from 7 to 15, a density of from 0.93 to 0.95 g/cm³,a weight average molar mass M_(w) of from 50,000 g/mol to 500,000 g/moland has from 2 to 6 branches of side chains larger than CH₃/1000 carbonatoms, a z-average molecular weight M_(z) of less than 1 million g/mol,wherein 5-50% by weight of the polyethylene having the lowest molarmasses has a degree of branching of less than 12 branches/1000 carbonatoms and 5-50% by weight of the polyethylene having the highest molarmasses has a degree of branching of more than 1 branch/1000 carbonatoms.
 9. A polyethylene which comprises a mixture of ethylenehomopolymers and copolymers of ethylene with 1-alkenes, the polyethylenehaving an Him of 7 to 60 g/10 min, a molar mass distribution widthM_(w)/M_(n) of from 7 to 15, a density of from 0.93 to 0.95 g/cm³, aweight average molar mass M_(w) of from 50,000 g/mol to 500,000 g/moland has 2 to 6 branches of side chains larger than CH₃/1000 carbonatoms, a z-average molecular weight M_(z) of less than 1 million g/mol,wherein 5-50% by weight of the polyethylene having the lowest molarmasses has a degree of branching of less than 12 branches/1000 carbonatoms and 5-50% by weight of the polyethylene having the highest molarmasses has a degree of branching of more than 1 branch/1000 carbon atomwherein the polyethylene is produced by a process comprisingpolymerizing ethylene in the presence of 1-alkenes with 3 to 12 carbonatoms in the presence of a catalyst composition comprising at least twodifferent polymerization catalysts, wherein A) is at least onepolymerization catalyst based on a hafnocene (A), and B) is at least onepolymerization catalyst based on an iron component having a tridentateligand bearing at least two aryl radicals with each bearing a halogen ortert alkyl substituent in the ortho-position (B).